For the 50mm and probably the 85mm it's probably a matter of intended use. The 50mm L simply has a specialized use than the 1.4. Not as sharp as I'd like (and neither is the 1.4) but at that price you'd better be able to justify it - and people do.
Although that might be true in general, there are plenty of exceptions. The 50mm f/1.4 85mm f/1.8 and 100mm f/2.8 macro will either equal or better their L series counterparts.
You got me on that one. I use my 50mm f/1.4 almost exclusively for the few portraits that I do. I have a neighbor with a 50mm f/1.2, and I honestly don't see enough of a difference to justify the price difference.
My point is, though, that I will save up longer to get an L, after doing my homework, of course.
