Either they use the larger pixels in larger numbers or they don't.
If they don't need larger pixels then it is possible to put the same pixels into a smaller space. In that case they are not taking anything away from those professional. It is the same functionality in lighter, more portable equipment. I don't know many professionals that need to move around that like lugging around stuff that is more heaving and larger than it has to be.
For example, the new Nikon 800 takes photos that are 7360 x 4912. What is going to be better at displaying all those pixels to the "pro". A 1920 x1200 screen or a 2880 by 1800 screen ? Similarly for high end video folks moving to 4K resolutions. Better on 1920 x1200 or 2880 x 1800 ?
(and if need a fancy external full size, standard pro studio monitor , then don't need a 17" screen
http://www.aja.com/en/products/t-tap/#/overview )
If Apple killed off the 17" display and didn't add a higher res 15" screen that would be a regression. This can easily be moving forward if the rumored more high density screens roll out, but with a smaller form factor.
This is just the FUD spread when some minority niche wants to puff themselves up to be more significant. The Mac has always been created for everybody. "The computer for the rest of us" .... not "The computer for the artsy elitist" If all the non a/v folks had not bought Macs over the years the Mac would have died off long ago. The a/v crowd didn't save the Mac by themselves. That is just often repeated folk tales.
If those people bought Macs and got a good value then they made an equivalent exchange with Apple. Apple doesn't "owe" them anything any more than they owe Apple something (are required to buy an Apple product in the future).
Fact is that in general over an extended period of time computers tend to get smaller and more capable. Primarily, that is the factor that is killing off the 17" Mac.
