It isn't weird to wear mtb shoes on a road bike. Many people do and for just the reason you mentioned, walking is easier. There are some riders who wouildn't be caught dead in the "wrong" shoes, but they have more problems than their shoes.

Use what works. Don't worry about what others think.

I wear Shimano mtb shoes on my road bike and my mtb. Cheaper that way and I'm still searching for the perfect shoe...

sarah