Kylo is part of the knights of Ren, we see them all wearing masks in the force vision scene, so him wearing a mask may be related to that. Or it’s becaue of his worship of Vader, which makes sense as him being Kylo’s very powerful grandfather.
We saw Luke for only a few seconds, I’m sure the next episode will show a bit more of this island and what Luke has been doing there.
My issue is Vader wore a mask for a reason and never took it off. I always thought bobafett was a humanoid until we saw PT where his dad took his helmet off and it was a kiwi underneath, why does ren take it off any chance he gets, just seems pointless. Are we going to see more storm troopers without helmets on, it takes the sci fi out of it and normalises the whole thing IMO.