You guys are picking and choosing my points. I will lay them out:
If you want a refund, contact the Developer. Most reasonable developers will refund your purchase if the app is broken. There's really no excuse for not simply sending an email.
There's a big difference between having to ask (with the developer having the option to say no or ignore you) and having it be automatic and something you can count on.
15 minutes really is enough. I can't think of a single app that I have bought that couldn't be tested in 15 minutes. If it takes longer than that it's obviously not horrid enough that you're willing to put up with for at least a few hours.
You're simply wrong on this. If you can't think of apps that take longer than 15 minutes to test, think harder. There are plenty of good examples in this thread.
I will use one of my apps as an example.
I have an application on the market in both paid and trial form. The paid app is refunded 72% of the time. Now before you claim that it's because I wrote a bad app, I will mention that the paid app has a rating of >4.5 stars and a majority of 5 star comments somewhere around 25:1. Nearly every comment is about how fluid the app is.
The problem is that people don't want to spend money. After purchasing they have buyer's remorse and refund their money 2 hours later. If the refund window was 15 minutes from the start, I guarantee their would have been little outcry, and more people would have learned that the refund option is not equal to a trial.
Actually, it is supposed to be a trial. Since there's no inherent trial mechanism built into the market, there's nothing wrong with people treating it as a trial. And those people who don't want to spend money (the 72% of the time you get hit with a refund) probably just won't bother trying your app. And some of the 28% whose sales you do retain won't either.