This sounds a lot like the Outlook 2007 discussion on Vista (and some reports on XP). Vista has "advanced memory management" and Outlook "continually asks for RAM, as long as some is available". The result? Outlook allocates ~700M, according to the Task Manager process list, while the Physical Memory free (on a 3G system) reports 6% free. Closing Outlook brings the ram free percentage up to %60. Some MS MVP said just what you said "The RAM is available, so Outlook uses it and the program responds faster, that's a good thing", completely disregarding the fact that the computer is near unresponsive to everything else. A program should never take RAM "because it's available", it should take it "because it's needed". Using over 2G of RAM to open 3 emails is absurd, using 1G for texture and sound data is more reasonable.
MS has a very nasty habit of making its software defaults benefit MS rather than any particular user, even when a cursory installer examination of the user's machine would suggest different settings.
MS wants things to be oh-so-shiny! Many of us prefer our systems to run oh-so-fast. As a rule, I never select MS's "recommended" or default options when adding, or changing, or updating software. When you consider that spyware such as WGA stuff gets installed by default in MS updates, I don't think I'm being too paranoid.