Limited liability is a very good reason to incorporate, even if it costs you a bit!
Luckily for the OP he is likely in a relatively safe position. If his app store money fails, he likely has the talent to quickly jump into a development job somewhere else, and not have any capital tied up. So long as he keeps well away from debt, incorporation isn't a big deal. However, as he stated he wants to make more, which tends to incur risk-taking, which limited liability is ideal for.
I've seen several horror stories of genuine hard-working people lose almost everything because they were fully liable. Yet I've seen some very lazy, non-talented people lose virtually nothing because they incorporated. I know of one guy who lost hundreds of thousands, and still managed to retain control of his business after the banks stepped in. They now own ~40% of his company, but he's still earning the same wage.
Forming an S-Corporation can reduce your tax burden. The filing is a bit more complicated and you have to pay yourself payroll, but you would be looking at reducing your tax burden on a portion of your income by about 7%... That is, going from 25% tax rate to 18%. Definitely worth doing.
Incorporation can help with U.S. taxes by enabling a tax-free retirement account with a large contribution limit. (SEP-IRA has a 25% of salary / $49k annual contribution limit.)
