I'm not speaking about profit motivation.
Right, but it started out as a free to play PC game, so it seems pretty clear that profit was a secondary motivation.
Different platforms have different types of software that is suited to them. That's why the DS has a huge library of titles that you will never see on other machines, and when games get ported to the DS, they tend to get redesigned to fit more with the handheld culture.
I'm not sitting down at my desk and booting up my PC to play Cardinal Quest or any games like it. I'm not too fond of squinting to see a tiny black playfield hosted on a web page with a bright background. Despite how great I think it is, it's just not something I'm going to bother with as PC Software. Turn it into mobile software, and suddenly it's very different. I love it, and play it all the time. I'm anxiously awaiting the sequel!
I see tons of good software being made, and it sits unnoticed on the indy game programmer forums. They also bitch that can't program for any consoles because they are locked down, etc... meanwhile, Android v2+ is the world's most popular console like device, and the only barrier is a 1 time 25$ fee. And people making software of similar styles and quality are making money and getting exposure off them.