I recently just changed the payment tool I was going to sign up and use because they asked for a "numbers only" password. This is not flimsy, I would surely for

I recently just changed the payment tool I was going to sign up and use because they asked for a "numbers only" password. This is not flimsy, I would surely forget any password I had to create with this restriction. If your startup is on a competitive market, with no unique service only you provide, I would make it simple, letting the users make their choices.