If the Imperial Guard ever do get added to the lineup wouldn't they have to be Traitor Guardsmen? How else would you explain some IG firing upon four of the greatest chapters? That would no doubt leave a lot of people disappointed for not getting their favorite Regiment, though.
Problems is, Imperial traitor are allied to Chaos. So we have SMC and Imperial traitors.. Not easy to resolve. Fridwell, a Flak armor in all books, in all movie, is useless look at Space Marine you one shoot them with your bolter.
Imperial Guard are just humans like you and me with a laser. Pew pew. That's why you need soooo much Imperial Guards to get an enemy down. So if you could play Imperial Guard, you would be squashed every time by any other race.
Have a look at Black Industries and FFG's RPG lines for surviving bolter fire. In Space Marine you can one shot them, but they can also survive more than one shot. They have more than just "pew pew" lasers though.
It's 100% true, just if you thing imperial are so strong, why there millions of reregiment with millions of soldiers and they don't control the Universe ? Why they called SM Angels of death ? Why they always flee the enemy ? You think they can rivalise with SM in same numbers ? Stop taking drugs ! So funny but so true ^^' Pew Pew !
Well impy goo mostly consists of las rifles that can't kill a space marine or orks (need a headshot for orks)
They have more than just Lasguns but only veterans get those and even then they're hopelessly outclassed. You survive because of dice rolls not because the armor actually works, it's like oh you rolled a 1? The Bolter Shell decided it was too tired to go fast enough to penetrate paper. In every piece of lore you can find Guardsmen get OBLITERATED by Bolters.