Unfortunately, post numbers 53 and 54 below yours illustrate why updates should be released as soon as they're 'ready'.
Some people (what percentage of total users exactly, I'm unsure) suffer from bugs in OS X which may only be exposed by their particular configuration. These need to be addressed ASAP. As we know, these updates can trigger problems for some that weren't present in the previous release, but I don't think anyone could argue that, overall, 10.4.7 isn't a great improvement on 10.4.0.
Another simple truth about software is that no matter how thorough the testing, certain bugs are only going to be exposed by letting a few million pairs of grubby little mitts on the product. Personally, I quite like the current situation. Admittedly, I've been lucky - no problems caused by updates (barring the 10.3.7 -- or was it 10.3.6 misstep). It's nice to think that whenever a quirk shows up, there's a decent chance it'll be addressed within 6-8 weeks in a point-release.