The updater is just plain buggy. Ed Bott mentioned the problems with limited user accounts, but I didn't see him mention the issue with jucheck ignoring the update settings:
http://superuser.com/questions/130961/how-to-stop-jucheck-fr...
I also had an XP system where the %appdata% environment variable somehow got deleted. This completely breaks the installer.
I picture some Oracle bean counters decided that once a month toolbar installs is decent revenue for them without pounding their update servers too much with requests to see if the new version is out.
Also, where is ask.com getting all this cash? I don't know anyone who uses it.
Apparently most people who use Java use the ask.com toolbar. </sarcasm off> Edit: With the ask.com toolbar installed, it also changes your default search provider, and it is very hard to put it back in some cases. So I'm sure that's where they get their money to pay for the drive-by install.