For those of us who didn't get our formative ideas from cheap sci-fi movies, the obvious problem with the "we're living in a computer simulation!" notion is that it's precisely the same babble as the "god made everything!" argument. It's a pointless regression.

For the people who think god is the answer to everything, one must merely ask "where did your god come from?" and we instantly see the god idea solves no problem. Likewise the simulation idea solves nothing at all, for then we must ask "where did the simulator-builders come from?" and we see we have introduced merely another pointless regression.

In short, it's better to engage with reality than to attempt to distort reality to fit a half-baked sci-fi plot device.