Microsoft and Apple have put a lot of thought into the security architectures of their consumer hardware. I've made this exact argument before -- just put the ATM app into a console title. It's the most secure hunk of readily available computing hardware, right off the shelf at Target.

But breaches happen, and lead to lawsuits, and I can just imagine trying to impress a jury about the security of your ATM while the other side cracks jokes about gold coins in Super Mario and speculates about your low Halo ranking.