Why is it that people think that every device has to do everything and be everything for everyone (and all for just $499)?
Multitasking? Serious database work? Programming? Large spreadsheets? Virtual machines? All these tasks I do comfortably on my iMac and my MBP. I'm not thinking of getting rid of either. I'm buying the iPad because it promises to be great at what you termed "consumption (reading, playing games, watching movies)." Why would I want it to multitask?
On top of that if I find myself out with just my iPad I *could* create a document or spreadsheet, or write a long e-mail, etc, maybe not under ideal circumstances, as you say, but it's an option and choice is good.
Also, to be honest the iPad would perfectly fill ALL the home computer needs of my girlfriend and be a far better experience than the netbook she struggles with now, why be derisive of that? Not everyone needs to be a 'serious' user.