Conversation so far:
When was reformation released for the The Smashing Pumpkins?
On June 21, 2005, Corgan took out full-page advertisements in the Chicago Tribune and Chicago Sun-Times to announce that he planned to reunite the band.
When was the reformed The Smashing Pumpkins' album released?
Zeitgeist released on July 10, 2007
What happened with The Smashing Pumpkins' reformation?
there was question as to whether other former members of the band would participate.
Did former members of The Smashing Pumpkins want to get back together with Billy Corgan for the reformation?
In April 2007 Iha and Auf der Maur separately confirmed that they were not taking part in the reunion.

Question: Why didn't they want to join the reunion?
Self-contained rewrite: Why didn't Iha and Auf de Maur want to join The Smashing Pumpkins reunion?