Why aren't they?
Perhaps.. perhaps.. dunno, I may simply talk to the wrong people, but some of the Linux people I'm referring to are, dunno, 'different', just oddly different. Different ideas than other people, different OS/software ethics. When I'm making some retro game editor they immediately are asking me why I don't make it open-source, as if closed-source is a sin. If we'd be talking politics, these people would be so incredibly tree-hugging left-wing regarding 'power to the mass' and no power to a company (Microsoft in this case). In the many discussions I do with them about several things they always come up with oddly different opinions 'n things that make you scratch your head.
As for the "why aren't they?", could it be that this group o' people prefers an alternative way of thinking and living, mixed-up with a certain aversion of how things are done or solved in the world of Windows? I can sometimes imagine that their way to deal with computers and software totally not matches that of non-Linux people. If this is structural (I just know a few Linux ppl) then I guess Windows and Linux software will always be different.
The worst part is that these Linux people I know are actually rather intelligent, having done seriously technical studies etc. It's just that they're sometimes *hard* to communicate with, 'impossible' at times..!