But what about the tanks? We can't just give LRBTs and Baneblades to the Space Marines, they'd never drive a Predator again! IG absolutely needs to be an independent faction, for the tanks' sake.
In faction fighting makes sense for the Imperium troops. Even SM Chapters have fought against each other over small matters, some are even known for teleporting out of combat rather than fighting along side with IG. Now imagine all the infight of the Ordos, Inquisitor against Inquisitor, Commissar against Commissar, Planetary Rulers playing against each other and so on. Whole Armys declared renegade for trivial matters, all this disinformation, false information, rumors. Now add in a hefty amount of zealousness, single mindedness, fear, propaganda and what you have is the Imperium. Its a wonder the imperium still exists. True its not an everyday matter for a SM to slaughter IG but it happens more often than you want.
i wonder if people are actually putting any thought into wanting IG to be in the game. Especially as an independent faction. i'v said it once and i'll say it as many times as it is needed, Imperial guard go to way by the MILLIONS. with THOUSANDS of tanks. This is of course in no way possible to recreate in a game. Plus you need to factor in the number of players for such a faction. I have no doubt that there are plenty of people that want to play as IG but nowhere near enough to make up an effective force which is even REMOTELY lore friendly. Adding more factions only thins out the number of players for the already announced factions even further, and then you'll need the ones to fill in said faction you want to add that being the Imperial guard of all factions. these guys run around in 10 man infantry squads, 2 man heavy weapons and average vehicle crew of 4. how do you propose to have the people to do all of this? have 2 imperial guardsman be equal to 1 chaos space marine? oh man yeah that'll make people happy and want to keep playing. i'd hate to see small groups of 4.. 6.. maybe 7 guardsman running about with a single leman russ or chimera driving around somewhere. and making then all stormtroopers isn't really a great way of doing it either. adding them to the inquisition won't do much good either. Aside from the rather large forces of chaos running around, it seems odd to have such a large number of inquisitorial members on a single planet(besides if chaos was that bad they'd either send the GK or Exterminatus the hell out of it.) As much as i would love to have them playable, i just don't see how you can do it properly(and even though is of course more important) and keep it remotely lore friendly.
maybe the IG lost 90% of the fleet in a Warp Storm and the only ships that made it are Karskins / Ogre and whatever special troops they got along with a handful of 0815 IG. There are always ways to explain it with the fluff.
I have played quite a few shooters. I have never played a shooter where an enemy was completely unable to see you no matter what he did.