XMPP support is alive and well. I don't know why microsoft didn't integrate it, but that's another matter (it may be argued that the google video chat never truly worked on open standards, and rather than implement a "broken" IM they just preferred to leave it out )
Anyhow, the only real reason to stay separate would be to compete with each other, with the slim chance to push the competition out of the market (at every services' users expense), and I agree how this has come to be a sad reality
