@Bajax @histoire
I think it could be because dogs are better at emulating human expressions. We seem to be more likely to think a dog is smiling, frowning, surprised or whatever just by looking at their face. Which means it's much easier for people to empathize with dogs than with cats. If anything, this could actually be their most evolved trait that enables them to live with humans.

Cats do have their own little adapted trait, but most people don't even realize it. Apparently, meowing isn't actually used to communicate among themselves (except with kittens). Cats really do meow just to get your attention.