Unfortunately, not EVERYONE is on broadband, and for dial up users, the bandwidth taken up by Windows Update can deeply irritate browsing habits. Also, I find that when on a dial up connection, you end up many months behind the current updates, with the lag getting greater as time goes on, as the updates are downloaded so very slowly. Then there are those glitches which need to be fixed by six other updates, all a long time time to wait on dial up, especially if your PC starts to crash because of the problem.
Then, there's that thing we can all sympathise with, that moment when Windows asks to restart whilst your in the middle of typing a lengthy post. You only need to press space to suddenly lose control of your system.