"This makes sense"
"People should have expected this."
"How else do you guarantee minimum performance?"
Make a regular m.2 slot, have microsoft provide a "X series certified" program where SSD manufacturers can pay a nominal amount to have their drives tested and so they can put a logo on their box. Have a testing program built into the series X machines that can test all non-certified drives and reject if a drive can't reach minimum performance metrics.
This isn't rocket science, the proprietary connector benefits no one but microsoft as they can control the hardware, and if you don't think there will be a significant markup versus non-microsoft hardware of identical performance you are truly kidding yourself.
That said, the vita comparisons aren't completely apt... For starters, these systems actually come with 1TB of storage where as the base vitas came with none, and the 2000 series a paltry (even for the time) 1GB. You literally had to buy a memory card when vita first launched to even be able to save on cart games, this is obviously not the case here. It's still a stupid practice, but it's hardly as bad as how Sony fucked up and continued to fuck up when they released a revised model.