You need NFC (which many Android devices have had for years)... but you also need an actual secure chip (not a software emulation or intermediary), and the ability to initiate payment without having to turn on the phone or type in a security code (i.e. a fingerprint reader), and you have to be able to do it with the phone locked and turned off (meaning you need low power hardware to detect the NFC and wake the phone up). And then you need the OS integration to make it all work together seemlessly. And it has to not leak information to anyone except your bank which obviously needs to have the information anyway... and there is no smart phone app on the market other than ApplePay which can make that guarantee. Certainly not Google Wallet. Or CurrentC. Or anything else. And it's better than chip-and-pin and tap-to-pay which both have physical security issues (though they are much better than mag stripe).
Android is missing too many pieces and it will be at least 1-2 years before it has them all. And even then there will be such a huge percentage of *new* android phones that won't have all the pieces that it will only create mass confusion for the general consumer.
The reason Google Wallet has been a failure to-date is that it (and all other smartphone-based payment systems except ApplePay) is simply not convenient to use compared to swiping a credit card. The reason ApplePay became the #1 smartphone payment mechanism overnight is because it's utterly trivial and convenient to use.
It took me exactly 3 seconds at the local Whole Foods to pull out my phone, tap it with my finger on the finger print reader, and put it back in my pocket. It takes me about as long to swipe my card if I don't have to sign, but half the time I do have to sign so ApplePay immediately wins because I never have to sign (at least not so far).
Eventually all smart phones will do it the Apple way. For now, though, and for the next 1-2 years at a minimum, Apple is the only smartphone game in town that actually works well. Chip-and-pin and tap-to-pay cards work almost as well... they can even be more convenient in some situations, but they don't cover all the security bases.
-Matt