I know a few people who have repurposed bags for their dolls, and it's a great way to save money and find something that fits just right.
I think if it's the right size and you're happy with how it looks, there's no reason not to use it!
A lot of the bags marketed for dolls can be overpriced, and I'd rather spend on their customizations instead, so a DIY can be a good solution!
Just be sure the inside is clean and free of anything that could snag on the doll's clothes or wig.
You might also want to consider adding a bit of padding or a soft liner to the bottom and sides for extra protection, especially if you're carrying your doll around a lot.
Putting a simple piece of fleece or foam can make all the difference!