I believe the main purpose of the front height speakers in a 9.1 system is to make music sound more like a live perfprmance rather than make movies sound like your in a theater.
I would think that all of the folks that couldn't live a day longer without being able to decode the new blu-ray sound formats in their processors, even though only a few dozen discs offered them as an option, will soon be unable to live without 9.1 processing.