Claiming that your OS is superior then complaining that the software you want doesn't run on it seems to counter the general theme of your argument. I've nothing against Linux, but it seems the big downsides are that it doesn't have a single source release so support costs for consumer
level Linux software is often inordinately high (compared to other platforms) and the consumer level install base is very low which probably puts profit margins into the red or uncomfortably close to it. I'm sure it's technically feesable and probably quite simple to get a lot of OpenGL programs running on Linux but that alone doesn't mean a company can make money from it. Mac's actually have a sizable and growing share of the consumer
market and they're easy to support because of the fixed hardware release model Apple uses.
Unless Ubuntu or some other study can show consumer Linux usage stats that match even half of what Apple has and that those users have sufficiently powerful GPUs/CPUs for gaming I can't see Valve supporting Linux for at least another 24 to 48 months. From what I understand, a big chunk of current consumer Linux use is actually for cheap non-gaming capable netbooks so the actual % of gaming capable Linux machines is far too small to support the financial overheads of a steam rollout.
The crux of the problem isn't a technical issue but one of dollars and market share.
p.s. You can't assign an increment operator so the expression in your sig would throw a syntax error.