Killing imap would cause 60-year-olds I know to complain at the same time that we would complain. You can't have that broad spectrum complaint. As much fuss as there was over whatever that RSS thing was, I signed up and used it for 6 months and then forgot it existed.
In short: Let's put to bed the idea that Google is arbitrary, they're not. If they look at the numbers and see people not really using the product, they take it out back and put a hollow point through its head. (This is also why I'm bullish about Google Plus...they would have killed it otherwise.)
Ask them about IMAP and their response would be "What??". Your point doesn't support itself.
I tried to type out another paragraph but it was equally as bad. Here is another shot at what I'm trying to get at: They're not the same because I'm willing to bet there are orders of magnitude more users using imap than there were technical people who used and cared about Jabber. Even as a technical person, I hadn't realized Google had removed it and I'm someone who previously used it. And I'm in the small group, not the general public, but I know several people off the top of my head that aren't technical and myself that use imap on a daily basis.
Federation, the ability for having your own jabber network contactable by google talk users and vice-versa, that was (partially) turned off, after a string of spam abuses.