My problem with steam wallet is that to add funds on it I'd have to pay a fee to the shipping company (pagseguro) or directly to the bank (which is higher lol). The mobile phone payment has a lower tax, therefore is a better option, but we're talking about a year subscription right? So that's not a big deal at all, it would be nice if implemented, but not as serious as if this taxation was monthly or weekly.
Let's all chill and cheer steam.