WRT XMPP clients: Dino.im is getting there (although it's still too early and buggy to say it's there yet, I think). I'm still not aware of any decent web clients though, unfortunately. The ones that do exist tend to be developed by individuals and full of security issues, even if they are nice looking and easy to use.

I tend to think that we don't need more small community projects, we need one or two entire services like Slack to build themselves on the base protocols and federate. Even if they only allowed their own clients so that they controlled the entire experience, if they just federated with other servers it would give users a choice and largely solve the Slack problem.