I think it's fine! I went to a shower earlier this year for a friend who was having twins. She has two other children who are around 6 and 4, so it hasn't been too long. They asked instead of gifts to bring diapers or a frozen meal. It was fun!
If I weren't such a picky eater, that'd be awesome. In theory, this is a GREAT idea.
My baby shower is a baby shower/diaper party. I know a lot of women on the Baby Shower board loathe diaper parties. There is a door prize for anyone who brings a pack of diapers, and it is listed as optional. I'm the first in my circle to have a baby, so I guess I sorta get to set the standards.