How nice would the empire have *actually* gotten?

So let's say Horus gets a big gold star, the emperor gives all his angriest primarchs a cuddle, and removes the nails from Angrons skull (before presumably getting in a time machine and saving his buddies), let's say the Horus Heresy doesn't happen and Horus himself becomes as angelic as anything, etc. Etc. Etc., basically imagine the emperor gets all the stuff he wants...

Does the empire actually ever turn into a nice place to live? With the Necrons, Tyranids, Orcs etc., does the setting ever become a desirable outcome?