Combining your wallet (or credit cards) with your cellphone, is foolish and personally irresponsible.
I understand the idea of consolidation and easy access. But phone snatching is so prevalent these days, because of how mindless phone droning makes people unaware of their surroundings. You’re basically just including your ID, credit cards, etc into one neat little package.
Spread out your loss and theft surface.
As a dude I have pockets to hold my phone and wallet. But if I were a girl their clothes often don’t have good pockets. I would probably carry my phone in a wallet case, keep track of your stuff and the rare risk (depending on where you go) is worth it.