That's your personal value judgement, and while you're entitled to it, the lens performs as it does, regardless of price. The $13K 600mm f/4L IS II costs $4K more than its predecessor. Are the optical improvements and lower weight worth $4K? Was the original worth $9K? Perhaps not to you...but does that make either lens crap? A Chevy Camero ZL1 has just as big an engine as a Mercedes C63 AMG, but the Chevy is half the price - that much better price/performance ratio that you're so loyal to means that Mercedes must be crap, right?
As for parroting the statements of others and calling a lens which is a favorite portrait lens of many photographers for good reason, and more importantly, one that you have very limited experience with, crap, well, thanks for being a shining beacon of maturity.
did you really just compare an American riverboat with four wheels attached to it to a C63 AMG to make a point and put the word immature on the end of it? judging from that alone.. you either don´t know jack about cars.. or you must be american.. if anything.. the 50L is a Camaro being sold for 20k more than the Mercedes.. but can´t handle fast corners (f1.2 and 1.4).. and all it has for it are fancy looks and a big engine (f/1.2) for the straights (portraiture).. if you find it justifiable to spend 800€ more for the 50L than the Sigma 50/1.4.. by all means.. it´s your money..
okay.. let me correct my harshness from before. the 50L is what it is - but for the price that they charge you, it ought to be a lot more of what it now just is not. i know you don´t give a furry crack of a rats behind.. but for the average consumer, the price policy of Canon in the last year or so (50L EFs have always been a bit silly).. is just plain ridiculous and you have to agree that although it is a creative lens.. if you consider what you actually get for your buck.. it is rather a bit of a pile of something - or if it´s the word that bothers you.. the lens is rather.. ridiculously over-priced for what it can optically do - the 50/1.4 for 400€.. is 95% as useful for 3.5x less.. and even you can´t deny.. the bokeh that the Sigma delivers.. is pretty darn creamy but just a bit less of.
and as for the big white thingies.. they tend not to sell that many, development tends to be just as high as with mass lenses, production is rather specific and more by hand than the mass ones.. the 9k$ in 1999 is about 12.5k$ in 2012.. when the 13k$ price goes down a bit.. yeah.. the new price is justified.