Fair enough. I imagine though, that the options would be as follows;
(1) permit multitasking apps across the board. This might mean a reduction in performance and not-so-nice interfaces. You and I might not care, but Apple probably does, and think it would harm the reception of the device.
(2) allow some apps to multitask (Twitter feeds, IM stuff). This is a whole can of worms - deciding which apps get allowance, how many at once, etc. Again, probably something Apple think would hurt more than it helps.
(3) side-by-side apps. People will ask, Why only two? Or will there be a desktop with windows? Or side-by-side with IM in the background or without? How to handle resizing? All these issues complicate things and are easy to suggest but aren't easy to resolve.
Finally, if someone thinks they are going to do enough copy/paste stuff, working across programs, etc. then they are probably better off getting a notebook, laptop, desktop. Yeah, the iPad isn't perfect for everything, but that's trivially true. In the future, it might be able to handle multitasking, but I think Apple made a reasoned decision (even if we disagree with those reasons) rather than just being obstinate or ignorant.