I can sort of see that, but I definitely still prefer the signs. I like going through either the whole areas or just bosses with coop partners, and those are the places where people leave summon signs generally, so I don't need the added "freedom" the bells offer.
Plus, with signs, you know right away if you can or can't get someone to join you. If there were no signs, I'd just mess around a bit by myself, maybe leave my own sign on the ground, try to do the area by myself, visit some other areas in hopes that there'll be signs when I get back etc. With the bells, I wouldn't know I couldn't summon anyone, but I'd still try. I'd stand at the same spot, ringing the bell for 15 minutes.
Some sort of a compromise between the two could be good. I really hope DkS3's coop plays just like DkS2's, just with none of that soul memory bullshit. Loved to help other people in that game, hated how I couldn't after a certain point.
That was a problem with the matchmaking, once they fixed it, it didn't take more than 30 seconds to find someone no matter where you rang the bell.
But they still did not address the issue of your inventory not replenishing after a MP session, which is why I stopped playing BB last month, I got sick of going back to the Hunter's Dream after every 5 invasions.