Hmm, as the title says

I can't find any that I like, and I'm wondering if I could just use, say, a large Longchamp tote bag?

I figure I will need these things:
- 4 nappies
- Change mat
- Cloth nappy / burp cloth
- Bib
- Wrap
- Nappy cream
- Wipes
- Cloth wipes (tablets)
- Toy or two
- Plastic baggies for soiled things
- Spare onesie
- My own wallet, phone, keys, lipbalm.

Apart from a few extra compartments, what is so special about a designated Nappy Bag?