Market share IS important. Apple needs to grow the base of machines that people are going to buy software for...
If you are a developer, and it's a choice between Windows, Linux, and Mac, some of the reasoning may go like this:
* Windows - well, I can't stand MS, but the hardware is ubiquitous, everyone has the OS, and the software is literally everywhere. I can grab a copy of CodeWarrior, and get going for not too much money...
* Linux - well, it's free, and the hardware is ubiquitous and cheap, and there's a great developer community.. I may not make any money selling my product, but I'll get to go to some really great parties. Maybe I can do well at consulting on it. Maybe I'll write something fantastic, and then I can do a book on it :-)
* Mac - well, it's sexy. It's Unix++ The hardware is pricey, and even with a $3000+ investment in ADC, I'm not getting much of a price break. My product will show up in some stores, but I better be really good at the download sales (a la OmniGroup, AquaMinds, and Circus Ponies) - I'm taking a big risk to develop something on a great platform that has a very small market share. Gosh, I believe, but I gotta eat too. Can't Apple sell a LOT more of these somehow, so that I have many more potential customers? Oh, do I go with my heart, or my head?