It's not a matter of being "stuck". I have functionalities that I use constantly in Leopard that I would lose if I upgraded. Losing them would be a severe impact on my productivity, with nothing gained to justify it. Just because you happen to prefer Lion doesn't mean it's ideal for everyone.I think a big part of these reactions is being invested and stuck in the habits of Leopard and not wanting change.
Also, for every quote you posted praising Lion, I could post two from people who had problems with it or simply preferred not to update. It comes down to personal preference, not solely the presence or absence of problems.