I personally really don't care at all for the ridiculous glassy look of Aero in Windows 7; it's ugly to me.
I think the biggest problem with Linux is that many people plainly prefer what they're used to. Additionally, if you're a so called Windows "power user" you have vested more knowledge in the Windows ecosystem - specialized knowledge that is useless in the Linux world. An older person doesn't have this specialized knowledge, computers are all the same to them. THAT'S why it's easier for them to switch. They're used to being n00bs and knowing little about the OS they're using. It really doesn't matter which OS it is.