The Tox protocol is really the core tool. As long as the protocol is well-defined and maintained, I think developers should be free to make whichever clients that they want.
I used tox ages ago, and I used the Blight client or whatever it was called, and I liked it pretty well.
I think a bigger issue is convincing people to use it in small groups. My whole team is just fine using Mattermost/Hipchat/IRC and the majority of them don't see the need for something like this.