The most often criticised "feature" of the Apple iPhone and iPad is it's single task limitation. Most analyses say it's because of battery life. But I think they keep this as a feature to protect the users from doing more then they can handle themselves with the device.

It's a fact that the human brain (especially the male ones) is not meant to do multitasking. Your overall performance doesn't increase just because you can open all your applications in parallel on your Computer. In fact it will slow you down because of constant so called context switches. You usually get more stuff done when you work sequentially on your tasks an focus all your energy on the current task.

And maybe that's the intention behind the single tasking of the iPhone OS as well ;-)