I'd say it's not that they don't want to be in the pro apps business per se, so much as they don't want to be a software contractor for big studios, which is what most pro app companies inevitably become. Apple wanted to make big changes, but mostly, big studios / production houses don't want big changes.
Avid probably couldn't make a radically different Media Composer even if they wanted. The risk of alienating current customers is too great, and the resources required to maintain multiple products targeted to the same market are too many.