I've only ever had a paperwhite but I've never had an issue with just moving my thumb over the screen a bit and tapping to go the next page. If it was a 50/50 split it would be and issue but it's not.
Yep. I've had buttoned eReaders like the Sony PSR-505, original Kobo and used early Kindle models. Buttons just aren't needed with the decent touch screens they have now.