One of the more annoying features of iTunes is its insistence on a full-sized download every time there's even a minor update. Steve Jobs apparently thinks that a 90MB download is "not so big", but Australian users might beg to differ.
Search blogger Danny O'Sullivan wrote to Jobs' personal email address asking why iTunes update files were so big, and why Apple couldn't provide smaller patch releases. Jobs' reply?
It’s about the size of one downloaded album. Not so big.
It's a mildly clever reflex reply, but it's disappointing for a couple of reasons. Firstly, in many markets, 90MB is a pretty big deal. Lots of entry-level broadband plans in Australia still only have 200MB of data before going into excess charges; a single iTunes update can chew up half of that, and it's certainly not unheard of to see two of them in a month. Not everyone has the unlimited download options common in the US, but as the iPad's rollout has demonstrated, the US continues to represent the main focus for Apple's planning and thinking.
More tellingly, it doesn't answer the key technical question: why can't Apple just send out minor patches? Operating system designers routinely manage to do that, despite dealing with a far more complex set of device interactions and a larger user base.
There's a few possible answers. One might be that running a full installer creates a more reliable process, though I can't say that's always the case (as the accompanying screenshot suggests).
Another possible explanation is that keeping everything in one installer makes it harder to reverse-engineer the code, but that's not really a justification for creating an update process that often makes users think "I won't bother".
I know several people who hold off on anything other than major iTunes updates, figuring that it's not worth the hassle and the bandwidth. The danger with that approach is that it can spill over into other updates and patches, with possibly more dangerous consequences. And while Apple isn't directly responsible for those decisions, its bloated coding practices certainly encourage them. Thanks Neerav for the link!