You may not remember it, but all of gamming since the NES has been plagued by sequels after sequels. You may remember all the single franchise hits, but many of those led to sequals and then to more sequals. Y's went to 9 at the least, Final fantasy is on 12, Mario is on what? 8/9 not including the spin offs, chrono trigger had a sequal, metal slug, bramuta triangle for the nes had one, so did light warriors, lemmings, and zombie ate my neighbors. If its a good game that becomes popular then theyll keep making it till it runs into the ground, theyve done it for a long time. Its nothing new. All that has changed is the volume of games being released (how many of those new ip(op, to early) are there that you easily over look?).