Well, most elites never see these prices. You only see them if you are buying tickets without logging in and after you enter in passenger information (without an AAdvantage number of an elite entered in). Only then, do you get the seat selection maps that show the prices.
Makes it real fun for non-statused passengers to figure out the cost of things when they have go through that many steps to see -oh crud- I have to pay $XXX on top of the ticket for us to sit together. Do I spend another 30 minutes looking at our options or just suck it up and pay it.

And, there seems to be creep up in both the number of seats being marked as "preferred" and the cost of these seats.

I think it is a crime that AA sells MC as a product that allows for seat selection (compared to BE), but then marks half the plane's seats as 'preferred' with ~30$ and up charges each way, each leg, each seat. Are you paying for seat selection or the opportunity to pay for seat selection? It's often the latter.