We would be that much closer to fulfilling our purpose.
We are here to transform matter into spirit.
Purpose is an extraordinary assumption, as is the even more extraordinary teological assertion. This begs evidence.
In any case, for all of the people and other animals who haven't "known" or believed that the universe is (just) a computer simulation, their suffering has presumably seemed quite real to them. So it doesn't seem to that the simulation creator is exactly benevolent.
Perhaps "simulation" is misleading. You presume an intentional programmer. Couldn't our situation be a natural simulation -- a dream, or an abstract, subjective reality based on sensory and processing deficits?
We know the world we perceive isn't objectively "real," so what is real reality?
But, conversely, for people who believe that the universe is a simulation, it seems to me that they are likely to view the suffering they cause to others as ultimately not "really real"
In which case the suffering would be as unreal as the view?
On the other hand, the issue that stands out in my mind is that the conjunction of the propositions "I believe the universe is a computer simulation" and "I believe I am truly volitional and can choose between available alternatives" seems to me to be, at least currently, contradictory. At least currently, we don't have a clue as to how to create a computer program that willfully chooses between available alternatives, much less a program where there are many billions or trillions of separate volitional conscious creatures who are volitional and acting autonomously.
There are levels of 'reality', and levels of volition. Even in our present state, free will is neurologically questionable.
The Neuroscience of Free Will
Well, transferring an objective moral fact and/or belief system to a computer simulation seems like a rather magical accomplishment. I definitely don't know how one would accomplish such a feat. I know of no gate or on/off switch by which to accomplish such a transference.
It wasn't so long ago that telescopy, telegraphy, horseless carriages and sound recording seemed magical.
How would a scientist of fifty years ago, with a slide rule, regard a pocket calculator today, much less a laptop?
Of course, given that there is a great deal of suffering that happens among humans and non-human animals alike, one can only wonder the simulation creator is ethically "responsible". Why didn't he or she create a simulation where creatures don't endure such suffering as found among creatures on earth?
The suffering itself may be part of the simulation. People enjoy reading horror stories; watching violent films and going to war. Could we not be participating in a virtual reality computer game, where the simulation will become apparent as soon as we end the game?