I'm tired of speculating why Apple chose to implement some things the way they did. Apart from the obvious which we've discussed, device resources. They obviously saw fit to temper that issue with a pretty heavy hand and in a rather inflexible way. And it's obviously a big deal for those people who only want "a little" third-party multi-tasking ability.

It's likely a matter of time before you're able to do more simultaneous tasks with at least Apple's own software. Their progress has unfortunately been rather slow on the OS and built-in Apps front. All the same, it's not something you want changing every few weeks either.

Fingers crossed things get better and there's more flexibility down the road. I'm still looking forward to the day we can delete or at least hide built-in applications, including swapping out a different music playing app for the crappy "iPod" app. But I won't hold my breath. Oh, I also despise mobile Safari and wonder if they'll ever fix the poor scaling in WebKit (which also affects desktop Safari betas and Google Chrome).