I think the official reason was that one of the seiyuu died.. not one of the important ones though, a minor character.
Anyway.. good riddance to that, it was 180 episodes of redundant nonsense. The characters have little to no growth, and Rumiko limits herself by writing in an villian who pulls the 'Ahahhh, beyotch, Ima regeneratin'!' card about 50 or 60 times. You can watch the first 20 episodes, skip to the end and still understand most of it. That's how little changes. Oh.. and speaking of the final episode, without doubt, the single worst ending I've ever seen. Sure as hell can't call it a final episode without any finality- Inuyasha and Kagome have a quasi-romantic moment and then the group strolls into the sunset, resolving to kill Naraku for real.
The only consolation I get from it is that the manga has got probably 3 chapters left.
