I think that if Piriform wanted to make the software better, then they should make it open source. With the source code online anyone with half a brain in software development could be of help. Like Mozilla for instance, being its open source, any developer can create extensions, add-ons, and so forth. Plus not only would Piriform be receiving free help for free software, they would be helping students like myself.
Its extensible in user add on inis. Though the idea that there is one semi official user add on (Twisted Metals) in my view is poor because Vista has different system and application paths to XP and it really requires a Vista user to do their own ini to fully cleanup on that platform.
If Piriform open source it they loose their IP and make it harder to sell it later on if they wished too.