"Sensible Defaults"
Given Firefox is intended for use by both technical and non-technical users, the default behaviour is both sensible for the non-technical users (most of whom wouldn't even know what a software update is, let alone why they are important or how to apply one), and easily configured by the more technical users if they wish to do so.
From a user support standpoint this is generally a good thing as it means the vast majority of users will get security fixes in a timely manner.
Even though it is a non-issue to me (I compile my own builds of browsers, and as a result don't use the update system), I really don't see the cause for complaint.
UserAgent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.8.1.2pre) Gecko/20070222 SeaMonkey/1.1.1




