[wusspuss]

>For messaging purposes, it is absolutely identical to JSON in this regard.

There's no "JSON mindset" to produce anything comparable to this crime against bandwidth and code brevity:

  <stream:stream from="draugr.de" id="{ID}" version="1.0" xmlns:stream="http://etherx.jabber.org/streams" xmlns="jabber:client">

Being sent on every connection for no reason, thrice (!)

>Once you have many existing implementations out in the wild that need to interact with each other, you'll need namespaces or their NIH analogue. And JSONs with namespaces will be just as bloated as XML.

Even XMPP, with XML, could do just fine without namespaces. The only place where namespaces are the differentiating factor in practice is <query/>'s and <x/>'s. Couldn't they just be be called <mam_query/> or whatnot? Oh, and namespaces specify the version. Like for ack's they specify the version 3 every time. But it's something that has to be (and is) clarified when enabling said acks anyway.