And there are people still using XP because they say 7 is a horrorshow. I've worked (in the last year!) with some salesmen at my company who still ask to be moved back to DOS because they can't figure out Windows.
Opinions are a funny thing: they're not always logical.
People are mostly still using XP because they said Vista was a horror show, and the upgrade path from XP to 7 is either extremely difficult or impossible.
You misread the versions. Windows Vista to Windows 7 takes about 5 clicks, yes.
But there is no direct upgrade process at all from XP to 7. It's possible to go XP -> Vista -> 7, but no sane person would buy a copy of Vista just to do that. Here are Microsoft's official instructions for upgrading from XP to 7.
First you export all your files and settings from XP. Then you install Windows 7, which is actually a fresh OS install and not an upgrade. Then you reinstall your programs and import your files and settings back in.
I've tried out the consumer preview as well. Can't say anything about how it performs because I tried it on VM but it had some obvious flaws that affected usability. I don't think we should judge them before the final release though. (or maybe we should wait till SP1 :D)
I've used it.
It isn't.
It's well and truly a horrorshow. And I like Windows 7.