I'm sure that with time wallets will become standard applucations. Smartphones companies closely watch the market and the trends and they don't want to stay behind. They are very well aware that many of their customers are involved in cryptocurrencies and they want high end service.
It's true that this is also security issue but I think mobile phone protection is developing very fast because it's necessary to achieve certain standards. We are having our lives stored on mobile phones, not just crypto wallets, and that requires extremely high level of protection embeded in phones but also very high level of user awareness and self protection.