First, a story. Both of my parents are ex-military. We have a red-beam flashlight from their service. The beam is red so that it doesn't kill your eyes once they're accustomed to low light. Recently, there has been a huge influx of all kinds of tactical flashlights on the market, with any color available. Everyone wants the new great thing. Unfortunately, there aren't any more gains to be made from flashlight technology, as far as color is concerned. Red is the best color to use, because of the long wavelength, it does not change our low light vision. Using a color such as green or blue will "reset" our light vision, and it will take about 20 minutes for our eyes to re-acclimate to the darkness.
http://homepage.mac.com/kvmagruder/bcp/instruments/redlight.htm
Regardless, a lot of people are buying "tacti-cool" lights in various colors, because hey, this is the 21st century! Technology must have progressed past our parents' knowledge!
The same has happened with headphones. It's not like computers, where processors are advancing so that they're becoming over twice as fast every year. There is only so much technology that can go into headphones. Increased automation can make headphones cost less, for a given material quantity. However, there aren't tons of things you can do overall. A $150 price point only allows for certain materials, but then you also have to factor in inflation. The K1000 weren't amazing, in that you can fairly easily mis-align them on your head, and they sound incredibly poor, especially for the price. I will venture that the multiple-thousand dollar headphones of yesteryear (Sony R10, Sennheiser HE90, etc), the current $1,500 and below headphones sound just as good: Ultrasone edition 8/9/etc, HD650/800, K701/K702, Denon D7000, etc.
Dynamic headphone research is stagnant. There's not much more that can be done. Or, if it can be done, we are so far up on the diminishing returns end, that AKG could make a better headphone, but there isn't enough of a market to support a K801 that is 10% better than the K701, and 4 times more expensive.