We have XMPP+Jingle, SIP+SIMPLE, OMA IMPS, and now this IMPP joins the club. Guess why people stick to Live Messenger, Skype, Google Talk, Facebook and (gasp) ICQ? These have providers and a pre-existing audience, and people don't care about the inner workings. You can have the best-thought-out, most efficient, open and extensible gem of a protocol, but how many people are going to download a (likely clunky) client and nag their relatives, friends and coworkers into installing it too? Yes, there are a few and we all know one; just wait until said project goes belly-up.
People started caring about gtalk's inner workings when they realized they could not longer see a lot of their contacts (the non-google ones) in the new "hangouts" clients.
Jabber precedes Skype. XMPP precedes Gtalk.
Seems like most of your claims are invalid.
Also, there's a new XMPP<->SIP federation standards in the works (it's still a IETF draft though).