It was inevitable it was going to happen, the same thing with all this craziness of paying to pay ´pre-release´ games. The problem is that the average game doesn´t have patience. Everything MUST be bought on release date. For this reason, the devs know that it doesn´t matter at all how good the game is or if it is finished or not, there is going to be millions of people who buy it at launch. There really has been no significant down-side to this for publishers yet.. I think AC.Unity probably got as close as possible, but even still, you can bet your ass the next AC that gets released will sell millions of launch day... people don´t learn.
I rarely buy new games on launch day, especially single player games.. there is just no reason not to just wait a few months, wait til it is fixed, and sometimes even cheaper. But I am not normal, and because of that Developers will see no reason to release complete games.