Sure, none of those are specific to the "computer" form factor. But they are all things that people think of when they think about their desktop computer (some mac and linux users excluded, of course: but that's still only 10% of the computer-using population). NONE of those items I just listed are problems with any "Tablet" computer.
The form factor is different, but so is the very model of user software and computing.
Of your 5 points - boot up and software update are reasonable. The other 3 can be absolutely issues.
The point is that they are not perceived in that way, so people are not scared of them. It doesn't matter how true it actually is, it matters what people think.
Phones take a while to boot too, but like most modern computers you just wake them from some kind of sleep mode when you want to use them.
Most phones don't use package management in the linux sense, so if Apps A, B and C are all using some buggy library that isn't part of the OS then who knows on what schedule they're going to be updated since you're carrying three copies of the same buggy library (This is ignoring side-loading and jailbreaking).
Something MS either doesn't get or can't admit publicly.