Because it cost like $10 and 5 minutes, could be set up by non-web-plumbers, and was pretty out of the box.
(I don't think Stallman's ideas are necessarily right for everybody, but I'm glad he's doing his thing right out in his end of the bell curve to counteract the opposite end of the software philosophy craziness...)
Web browser doesn't need to be set up, it is already included with iPad (or any Android device, or any laptop or desktop, or your smart TV, smart fridge or smart watch).
You need to configure your app during first launch pointing it to your data source, and maybe entering login and password. It is exactly the same amount of hussle compared to opening web site and make it default homepage of your browser.
I don't even want to talk about money, it's totally irrelevant, $10 or $0.