You dont honestly think he wants to sit in that chair forever?

When the Emperor returned from killing Horus he was so weak, he returned to find (possibly the 2nd greatest human / pysker) Malcador neigh dead. When he was inturred into the golden throne to take the strain (by which malcador literally turned to dust) he found that Malcador had saved a portion of his strength in his sacrifice to allow the Emperor to give a few meager instructions to his sons.

He never wanted things how they are now.
He wanted safety for the entire Human race forever.
What happens to those planets that dont want to join the Imperium / The Emperor? They will be eaten by the nids, killed and scavanged by the orks, or worse turned to the darker powers and then its off for a nice jaunt to the next planet be it imperium or not to sow more destruction.

You think too small and too little of the Emperor

Novel "The Outcast Dead":
An astropath accidently has contact with the Akasha-records (the repository of all knowledge of the universe, residing in the Warp). He has a vision of the future, that the Horus Heresy will end with the the attack on Terra, with the duel Horus-Sanguinius and the duel Horus-Emperor. The Emperor sees this and interprets it as him and Horus killing each other during the duel. The war will end in a draw instead of a victory for Chaos. And he's totally okay with that outcome.

The Emperor fully expected to die because of that duel. Except that he never died. He still sits comatose on the Golden Throne, while the Astronomican grows weaker and the Golden Throne exhibits weird malfunctions...

It's a sign of weakness for blaming your enemies for not being easily defeated. The Emperor declared war on the Chaos Gods, in secret, and informed none of his generals, alienating many of them. No, the failure is his and his alone. That's what happens when you assume responsibility for the entire fucking galaxy, it's your fault when things go wrong. Lorgar just did what he believed to be right, his worldview revolved on the Emperor being both just and divine, when he laid waste to the Perfect City just to teach Lorgar a lesson it showed him as unjust, worse, it invalidated everything Lorgar did in his name. Just because you clearly don't understand how important faith can be to someone doesn't mean that it isn't.

Is an iron grip necessary for survival? Perhaps. Does that justify everything the Emperor did? IMO, clearly not. If he'd succeeded then I'd be more willing to accept the Ends Justify the Means argument, but he didn't.

No, but he did want a totalitarian empire and I have every reason to think that after the Imperium's borders were secured he was going to go back for a round two and really tighten his stranglehold on the galaxy.

I think to myself, what if I lived on any of these planets pre-Imperium. When the Imperium comes it asks you to forsake the gods of your people in the name of their doctrine (that turns out to be complete bullshit), that you forgo your independence, and that you give up private industry, innovation, and progress to the fucking Cult Mechanicus, a bunch of cyber-weirdos with a hard-on for tech and no interest in sharing their knowledge with anyone outside their little club. If that was their negotiation, I'd of told them to go fuck themselves, and then they would have butchered my planet until the last pitiful survivors are either forced to submit, or are unfortunate enough to be assaulted by the Emperor's pet psychopaths like the fucking Space Wolves who thought that anyone who resisted the Emperor deserved to have their entire culture executed.

And Dorn was right, there was never going to be galactic peace, no utopia. Utopia's don't exist in reality and they certainly won't come to fruition in a grimdark setting. No, all you buy for your submission is the illusion of safety. You say I think too little of the Emperor, I say you think too much. You say I should have trusted in his vision, I say you're a deluded fool.

Man, Death to the False Emperor, Death to the False Emperor every. single. time.

Facts?
You do realize it was the Emperor who set up the Council of Terra?
You do realize one of the reasons that Horus turned coat is because he was giving the universe to the mortals and not to the transhumans who had fought for it?

No peace? Well of course theres no peace! Have you glimpsed out your starship window and seen Necrons, Hiveships, Chaos Fleets, Craftworlds and Emperor knows what else?
As it stands the Imperium is struggling valiantly but I say to you if we had 6 more Astartes Legions and innumerable lives not lost, we could hold our borders and prosper in a safer environment than any bar Terra today.

Clearly you are heretic scum and deserve to be purged with the rest.

The Emperor had a clear vision; humanity united in submission to his rule, with all internal opposition executed, all other races purged, and Chaos locked firmly in its box and kept from influencing the real world any further.

Many elements of humanity resisited his vision for different reasons - most of the compliances during the Great Crusade were achieved not by humanity embracing the Emperor's vision, but through military victories by the Space Marine Legions.

The traitor Primarchs questioned the Emperor's ends and his means. They knew that the Emperor's response would be "No. No questions. You follow my will and fight in my name, or I will destroy you and erase you from history."

Indeed, he had past form on this, even with Space Marine Legions.

Horus was simply the most influential of many to say "Actually, there is a third option. I will fight you, destroy you, and forge a new way for the future. And the forces of Chaos that you despise so greatly? They will be my allies."

That so many joined Horus in rebellion was not really down to his own charisma, or the seditious influence of the dark gods, but a reflection that the Emperor did not have the loyalty that he believed his totalitarian methods had achieved.

Neither the Emperor nor the Primarchs wanted the current Imperium to be the end result - that happened because the Horus Heresy was a pyrrhic victory for the loyalists.

Settle down lapdog of the corpse-god, if the Inquisition doesn't stop by to put down your little pack of mutants, I'll do it myself. For the good of the galaxy and the enslaved realms of man.

No real reply there, just insults, all your kind have left. Im sure given the chance you would rejoin us, but that will never happen heretic.

...I'm unsure what gave even the faintest impression that I have any inkling of a desire to be taken back into the fold, didn't mean to mislead you, I'm usually pretty upfront about my goal of shattering the Imperium into countless pieces.

What about the petty tyrants of terra? They've been a blight on the galaxy for millennium, not exactly seeing how that's a +1 team Emperor, mortal agents are easier for him to subversively control, had he lived to dominate the galaxy himself. Don't see how having a cabinet of administrators makes him any less of a tyrant.

He was going to give full control of the Imperium to the council of Terra, says it throughout the HH series.

Only a true heretic would slam the Emperor for his half finished work when its Chaos' fault he couldnt complete it.

Your argument is eloquent as hell and I think that we are taking the same situation and interpreting it differently. I will never forgive Lorgar and Horus for failing to hold the line. It may be a result of our modern world view that we think that it is always our right to ask questions and know the full picture but I have a lot of sympathy for the Emperor when he basically said, "Shut up. Do as you are told. I am doing something important here. I will get us there and in the end you will thank me for it."

I understand your point about the importance of faith, however in this case Lorgar's faith made him a poor soldier, a weak son and part of the reason that Humanity lost its shot at eternal dominance. Overall I see it as more of a case of a lack of discipline on the part of Horus and Lorgar than the Emperor's failing. He wanted it all and was close to achieving his aims; it was lesser men that let him down. I am much more sympathetic to your perspective on the idea that you have to win for the ends to justify the means though.