We are firmly shoes on in our house (dogs, wood floors, etc, it's practical- except for soiled shoes on the cream carpet upstairs obviously, we don't go that far). One of my best friends is firmly shoes off in her home. That's fine not a big deal, and we respect that and we all happily comply when visiting.
That said, one thing that's never made sense to me is when they host a fancy, grown up adults-only cocktail party, she still expects all guests to remove shoes. (They have tile and wood, carpets in the further lounge). So there is a pile of like 50 people's nice shoes carefully chosen to match outfits etc in the entry. 
In my opinion the point/ benefit of regularly not wearing shoes when casually visiting is so that your floors look lovely when you have fancy parties?!
opinions welcome, I'd really just love to know the thought process without accidentally offending my friend! 