No offense taken. I'm not doggedly set on defending 22k, though the geek in me looks forward to it. Your points are well taken.
Even if no other improvements are made in the move to 22k, and only 11% is realized, I wouldn't call that trivial. Moving from a P4 3.2 to 3.4 will only give ~5%. Especially in the recently stagnating field of enterprise storage, 11% is a big improvement. People have payed more for less.
In response to assertions that the viability of 22k hinges on value concerns, my example was just to point out why an enterprise would purchase 22k drives. Right or wrong, IT department everywhere have applied the same rationale to the purchase of 15k drives, despite a higher TCO and the ability to get an equally performing, cooler, cheaper 10k solution through more spindles.
From my experience, most IT pros aren't obsessive about the nuances of storage, though I am. Often decisions are purely based on brand (i.e. Seagate) and spindle speed. A Seagate 22k drive will sell like wild fire, even if it has you scratching your head as to 'why?'.
Personally, I wouldn't buy a 22k drive for my company until (unless) the tech shows some worthwhile advantage. However, I would love to have one for a server at home. It would be cool, and I don't need any reason beyond that.