The old gen still have a lot of customers so its not strange they get new titles, they also are very easy/cheap to develop to due to they cant handle any higher 3d gfx/resolution.
Second gen is also starting to get numbers but the dev's know its more work for each of those titles as they cant get away with the old lower quality as easily.
Third gen (Only higher end PC's) will be interesting to see, with the new 4k screens popping up that the already old "next gen" consoles only can dream about pumping any descent 3d gfx too. Just hope there will be any developers who pushes the boundaries here and make titles that not only take advantage of the higher res but also the extra power found in the upcoming nvidia (880 Gtx mid next month for instance) and Amd counterparts. Even more powerfull PC 3dgfx and their increased memory targeting the 4k's. Doubt the later sadly as the already old (second gen) consoles by modern PC standards will once again prove to be the gaming 3d gfx roadblock...
Note this is in no way in disrespect for the console owners but rather a cold glare at the lazy developers...