One of the problems I see with Vista is it runs appallingly on only 1GB. Now, before you say "Who only has that little?", not everyone is on 8GB monsters. In particular, when Vista came out, most laptops had 1GB. Windows XP ran fine on these machines. Windows 7 does too (even now, I'm typing this on a 1GB machine - a Samsung N220 Plus netbook).
Also remember that most users don't upgrade all the time. I tried to persuade my parents to get an XP laptop when they bought one about 4 years ago, but they wanted the new Vista... and are now still stuck with a slow Vista machine. It works okay some of the time, but randomly the hard disk decides to go off on a little adventure.
ETA: I think it's hard to blame the manufacturers for this. They couldn't just magically up the RAM on a laptop without increasing the cost. So on their 1GB machines, they'd have had to ship XP. It would indeed have been sensible for them to continue shipping XP, leaving Vista for the more powerful machines. But in practice, I can't blame them when they'd have just lost out in the market (people would see one machine with the "new" OS, and one machine with the "outdated" OS). It's MS's own fault for requiring so much RAM in the first place (and this mistake got them when netbooks like the Eee PC took them by surprise), but the least they could have done was just increased the minimum memory requirements to something realistic, rather than just giving a bare absolute minimum requirement.
I agree that a lot of the criticisms against Vista were unfounded - a lot of it was just the same criticism of a new OS, just like happened when XP came out. And the complaints about Vista asking you for permission to do things was just stupid, when (a) it's a good idea for security, (b) it's how other platforms work, (c) it's precisely what users of those platforms were criticising XP for *not* doing!
