Why did they kill off Maude Flanders?

Odd. There are several dozen voices on the Simpsons that we would all recognize instantly even if the clip was played just audio. Maude's character however had a generic female voice. Unless the actor was somehow assigned intellectual property for the Maude character, any of the current actors (except Kavner who sucks) could have stepped in and voiced Maude and no one would have ever known.

Also, I was under the impression that some character voices could be recorded literally anywhere and uploaded to the California studio for mixing.

Edit: I just Googled Maude and discovered that it was a pay dispute between the actress and the producers that led to her removal. For such a minor character and the couple of hours a year required to voice her, who the hell would give up a nice paycheck plus residuals over a pay dispute? The article did not explain why the producers didn't have one of the others do Maude's voice.

Second Edit: It seems that two women voiced Maude:
Maggie Roswell (1990–1999)
Marcia Mitzman Gaven (1999–2000)
Maggie Roswell (2002–present)

Source: http://simpsons.wikia.com/wiki/Maude_Flanders

Makes sense. Maude was a nobody without a discernible personality or quirkiness. Having Ned as a widower did open up several windows for Nedcentric episodes.