Download speed and CPU power have nothing to do with the way updates are handled. On an unrelated note, multi-core 3GHz CPUs are available for as low as 40? and broadband internet is pretty widespread now. I don't see why should the majority be bogged down by select few unfortunates still stuck in the P2 and 56Kb era.
The updater would be nice and convenient, however it is not absolutely necessary. We can live without it, unlike certain upcoming C2 features. Remember that Scirra isn't all that great in body count, however big their aspirations are.
Besides, I tend to be wary about auto-updaters, having gained a few grey hairs from update failures.