First of all, this is the dumbest gripe I've read in a while. If you're that unhappy, get a FF with a 24-70 and stop whining. Yeah, especially since this zoom would do things a 15-85 can't touch; it'd be reasonable to own both as they would be for very different situations.
Second, it's not even a valid gripe, as Tokina has a 16-28mm constant F2.8 that gets excellent reviews on crop. Are you really that concerned about the difference between 25.6 and 24?
And since I can't imagine it'd be that great for night photography at 15mm f/1.8 instead of 18mm f/1.8, seems a moot point.
The 17-55 could easily have been a 15-50. The 18-35 could have been a 15-30.Well, if you're willing to pay about 40% more, than 15-85 is gettable instead of 17-85. But, if you start adding 40% to all the prices of the Sigma/Tamron/etc lenses that go 17-50, most people wouldn't but them. It's one thing to get a $4-500 OS f/2.8 zoom; but by the time it's $6-700 there are other ways to go. Likewise if the 17-55 was a 15-50 that cost $1500. Going those extra few mm's means bigger glass, and more expensive lenses.
If it was so easy to make 15mm zooms, then why is Canon the only one that does?
You realize that 10-20, 10-22, 8-16 and 12-24 are all available in crop lenses, right?
Going a little wider isn't that big a deal, especially if you maintain the total zoom ratio. Longer is harder with fast lenses as the absolute aperture diameter has to be larger, which is why 70-200s are so expensive.