Human brain is not wired to multitask (see science articles) and is very easily distracted.
Multi-tasking may not be ideal or how we're wired, but it's required for a lot of work we do these days.
I can't much right my scholarly research articles if I can't have a stats program running and be pasting results tables into my article in word etc. I could do things like print the tables out and type them in I suppose, but that's less efficient and a waste of paper.
Add in that I need to have ready e-mail access to quickly respond to students and colleague etc.
I'll take multi tasking any day. My job isn't centered around focusing on on thing for long periods of time, but juggling multiple tasks at all times.
So no, it is not undeeded luxury item, it is much more suitable for content consuming than current computers (not only netbooks). Emphasis on content consuming.
Like I said in my earlier post--it does have a much better form factor for things like reading than a laptop or desktop.
But the fact that even those things can be done on computers we already own does make the iPad a luxury.
I'm not sure why you and some others are so defensive about it being called a luxury. It's not a slight on the device. Most all tech gadgets beyond computers are pure luxuries. Computers have moved beyond being pure luxuries as people just have to have them for school and work these days. But things like tablets, mp3 players, e-readers etc. are luxury gadgets as a lot of that stuff can be done on a computer, or one can buy paper books (or use the library for free) etc. so they are luxuries. Very few HAVE to have those kinds of gadgets for school or work etc. They may be nice to have and make some tasks easier etc., but they aren't required and all work could be done on computers you already own--so that makes them a luxury in my eyes.
And nothing wrong with that! I have an iPad, Kindle 3, a couple MP3 players, a nice TV, a blu ray player, DirecTV service, an Xbox 360 and on down the line and I LOVE all that stuff! But they're all luxury items. I don't need any of them to do my work, make ends meet etc. They're all for entertainment. The iPad does get used a tiny bit for work purposes, but not much as I find most work easier to do on a computer than a tablet, so the iPad is 99% and entertainment device for me.