I understand perfectly well that the 600/11 and 800/11 are aimed at birders. Based on AlanF's testing, the 100-500 + 1.4x is excellent at maximum focal length and full aperture. Having said that, he also found that the 800/11 outresolved the 100-500 + 1.4x.
I understand your desire for as many choices as possible. An 800/11 for $900, an 800/8 for $1999, how about they also make an 800/9 for $1500 and an 800/10 for $1123.46. Or better yet, 1/3-stop increments going up by $100 each? Of course, I'm being facetious.
But in all honesty, the 800/11 is a very good lens, albeit a slow one. In general, adding an extra stop of light adds significant cost, especially at long focal lengths where the front element diameter is a limiting factor. Even if they can make an 800/8 for <$2K, I doubt they will. If by 'fixed aperture' you mean a catadioptric lens, then certainly they can make an 800/8 mirror lens, and it could be even cheaper than the 800/11. But heck, if you want one of those and maximum reach, you should consider this:
Please don't put words in my mouth, it's insulting. I have never suggested that, "Canon provides absolutely everything that anyone could possibly want." Canon is a business. Their goal is to make profit.