I think that the main reason that WWE refuses to forget about Montreal is that, in their eyes, it is what helped them finally beat back WCW.
Think about it: Without the Montreal incident, there would have been no "Bret Screwed Bret" promo, which would have meant no hated Mr. McMahon character, which would have meant no "McMahon Hates Austin" stuff, which would have meant no McMahon/Austin "match" that had WWF (at the time) Raw beat WCW Nitro that night, and no continuing McMahon/Austin saga that helped people tune in to Raw.
They see that as what brought them to what they consider their second golden age (the first being the Rock 'n' Wrestling Connection era), and they just don't want to let go of it.