the accessibility that you get with these videos puts your work in front of an audience that wouldn't normally be able to enjoy it. i think that alone makes these types of videos valuable, but i get how it might feel cheap if someone simply uploads gameplay with no commentary/creativity put into it.
Absolutely no commentary videos are great for historical purposes/reference. A lot of times I'm trying to remember how a game work and instead of playing it I can just look at some footage on Youtube. If you work with games those are great.
On the other extreme, I enjoy videos with a lot of editing from people like Jontron and the AVGN. I saw some gameplay videos from popular youtubers that only play the game and talk over it without being funny or adding anything to it and those sure feel cheap.