is he a fairly new member of the family? if so, maybe he's still just testing out good sleeping spots and eventually he'll try new places.
but sure, if you feel like buying some cat beds, go for it. I think lots of us have done that thinking we'd give our kitties more comfortable spots to sleep but then have ended up giving the catbeds away cuz the cats never use them! ha ha! just depends.
you could also just experiment the FREE way for now and put out boxes or paper bags or blankets on the floor and on furniture to see if he wants to try those. I had a foster who just LOVED loud crinkly packing paper to sleep on. way too cute. I could always tell where she was, though.
and it's funny that actually some people would PREFER their cats not get on the furniture anyway because then they'd have to clean them more or they're worried about scratches in the leather or something.
Hey! just realized. maybe his prior mom or dad just trained him NOT to get on furniture, anyway, and that's why he doesn't do it. so it might just be the way he was raised. if you really want to change that, though, you should certainly feel free to encourage him. have fun!