I travel a lot to many different places including small villages. I'd like to take advantage of a rewards program, but the places I travel to often don't have one of the large chains. These booking services allow me to get bonus points. I thinks that's a good reason, besides the superior convenience of having a unified interface. I rarely had any issues with them either.

I once mentioned that while checking in at a family owned hotel, and they said they appreciate that the booking service allowed them to compete with larger chains on that front.