I remember going to the RSA where Jimmy Wales gave a talk about what wikipedia is suppose to be and what its not. In summary, he says that if wikipedia is to an encyclopedia, then wikia is to a library. Wikipedia was never meant to be overly specific, going down to every little biographical information of a person's life. That would deserve its own book just like you would create a new entry in wikia for that.
So what they did was justified. Wikipedia would go into a general summary of a show, a list of episodes for each season, character list, etc. But you should really compose the nitty gritty details for a specific episode or character on wikia.
The problem is that wikia is for profit, the administration is yucky (see eg the gaming wikis for doom and gta leaving it) and the local tyrannships of early adaptors makes it even more unpleasant to contribute.
So what they did was justified. Wikipedia would go into a general summary of a show, a list of episodes for each season, character list, etc. But you should really compose the nitty gritty details for a specific episode or character on wikia.