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.
The convenience of bundling is greater than my perceived risk of theft. Maybe if I lived in a place where pick pockets were more common, the algebra would change. Also, my wallet case only has 1 credit card and my drivers license. It's pretty easy to cancel a credit card, and a new driver's license isn't hard to get.