Not as simple as that. I actually took a look at the XMPP extensions list to see if I could replicate Hangouts on top of them. You'd need a new audio/video layer with support for centralised DSP, MUC and carbon copies at the very minimum. Not to mention typing notifications (do they work with MUC?), cross-client notification dismissal, automatic client priority assignment (if I'm using a client atm, don't ring all devices, just the one I'm using) and I'm sure a lot more.
Half of these things (e.g. carbon copies) are spec'd out but barely supported.
Hm, most of that is already supported (both in the spec, clients and servers) in user-to-user chats, I don’t know how difficult it will be for MUCs. Audio/Video is the problematic part here, I agree, but at least for me text is a big improvement over the times when I had to call people.
Would it not have been possible to offer a XMPP MUC as a text-based interface to hangouts, to allow ‘legacy’ users to still be connected?
As well as the OLPC extensions for transports to support application and screen sharing.
The X in XMPP is for extensible. I guess the point is Skype doesn't support XMPP or federation, and Microsoft is moving towards Skype and away from their SIP/SIMPLE chat services. Likewise, Apple's promise of an open standard for interoperating with Facetime turned out to be empty.
There was some discussion regarding the Facetime and open sourcing it on HN a while back, I can't find the source this quickly, but it was mentioned that Apple found itself on the barrel end of a lawsuit gun... and that because of that they have not improved Facetime much, nor innovated on it, or published any of the spec.
And as you say - there's a bunch of stuff to support if you go the traditional route and try to bolt on more crap to MUC or <message> stanzas. We're considering just building hangouts on top of "ephemeral" buddycloud channels that just disappear when the last recipient leaves them.
A very valid question. It was probably the outcome of a team meeting (don't we love them?), and one or more people were present with reasons not to take this route. What those reasons were, or whether they were well-founded, we'll never know.
They could publish these reasons to the angry users who are being cut off from their contacts by this. Not doing it shows the low culture of Google in regards to treating users. Evil or not evil, it's simply indecent.
Half of these things (e.g. carbon copies) are spec'd out but barely supported.