I've yet to find an MIM that outplayed an MIA. On the other hand, I've played Squiers that outplayed MIMs as well as MIMs that outplayed Squiers.
Mostly what you say is true, but back (a few years ago) when I was looking for a Fender Jazz I played LOTS of MIA, MIM and Squires. I DID play a couple MIA that were worse than the best MIM. In fact they weren't so hot by any standards.
But that was then and I hear that Fender has really tightened up on quality control these days. Good. It needed it.
For what it's worth I ended up with a nice MIM Jazz. Although admittedly it was not as nice as the best MIA I played, it was not the HUGE pile of cash either. Yeah, a reinforced neck would be more stable (though mine has NO issues with neck stability) and the MIA pickups (then) sound better too. But hey, even with new pups it's still WAY under the MIA price. But Fender has changed the MIM pups now too. So you have to be careful as to what you are comparing.