Where by "sucks" you mean "reveals what the actual picture you're going to get will look like", which on modern sensors is amazingly brighter than what your eyes think they see. EVFs are the future.
I've played with mirrorless, bought one for my kid, I think they are a joke if you are shooting as a pro. I just don't see why I would want one. A phone or a point and shoot will fit in your pocket and they do a great job. If you want better results you step up to full frame. Mirrorless seems like a solution to a non-problem. To me.