I'm suprised how vehement people's reactions to this topic have been. I've only read the first few pages and the last, and I'm astonished.
I was always taught growing up that if you were a guest in someone's home, you respected their rules and requests. So, if someone requested that I remove my shoes at their home, I would do so. If I didn't want to play by their rules, I guess I feel I should get out of their sandbox.
We never wore shoes in my house growing up. We wore them when DH and I first got married, but when we moved and had a baby, I instituted a no shoe policy. I just couldn't keep up with the job, the baby and the floors. It makes such a HUGE difference not wearing shoes. Also, you track all kinds of chemicals, etc. into the house, and with a baby who investigates everything with their mouth, I don't want them sucking on pesticides, lead, etc.
(BTW - Even Sesame Street has segments on it now that advise kids to remove their shoes so they don't track in lead.)
My ILs (MIL, FIL and SIL,BIL at their own houses) both recently started removing their shoes. I do so at their homes without being asked.
I ask my family and friends to remove their shoes at my house. I also ask small groups of friends. For the most part everyone has always been understanding. That being said, I warn newcomers ahead of time so they know. I don't think I'd want to be caught offguard (gotta admit, my socks sometimes have holes!

) I purchased slippers for my mom who comes over often and is always cold, and have offered to do so for others.
When we have large groups over (we only really do so twice a year, Christmas and DSs birthday) I do not ask guests to remove shoes, I just clean the floor when they leave.
Only once was someone really taken aback. We had a few friends over for New Years, and I forgot to mention the no shoe rule. Everyone who had been over before new and took them off no problem. One first time visitor looked stricken when I asked and said "I'll wipe them off really well." At that point, I made no objection and said "Of course." Just because I make requests, does not mean I am not a gracious hostess.
This is definitely a cultural thing. And has a lot to do w/ individual's attitudes. But, my opinion is, its your house, do what you want. But, just be considerate of other's needs. For those who criticized someone's hosting, I feel that the job of a host or hostess is to be in charge and in control of the party, but to accomdate everyone's needs as much as possible. So, make your requests, give people notice, and then accomodate individual scenarios.