Totally agreed on all points. Still, it's probably good for astro. Even shooting the moon with my 600/4ISMkI and a doubler, I had to shoot uncomfortably high ISO on my 1DsMkIII just due to the moon rising speed. (I think I shot 1/180th and even then the moon was moving at least two pixels up.)
And, make fun of collectors and fashionistas if you want but their money's as good as our money. There are dozens of car brands whose entire mission statement is to sell cars their customers don't "need." If you make a lens that sells to 100s of collectors at $10k gross profit, you're making millions there, but the halo effect is probably worth more than whether a specific lens is profitable or not. It's quite common in the auto world for top models to cost far more to make than they sell for, but they make the brand a star in buyer's eyes.