Seriously? Stop projecting. The new MBA no doubt will find its way into the hands of DJs and other live musicians.
Load a few software synths and huge sample libraries while tweaking audio tracks with live fx and come back to me with your results. Because that's what *I* will do when I get the 11" SB MBA as my only computer.
Okay maybe you might run over 4GB but your usage is pretty niche.
Just have 2 windows XP versions in parallels and try to OCR a dozen or so PDF's in Acrobat and you are lacking quite some memory if you have 2Gb installed. Even with 4Gb I see my MBA 13" ultimate starting to swap quite some data.
I prefer the 13" because it has so much more real estate, but I can see people easily using an 11", i7 and 8Gb without ever having to edit video or photo's.
So for the minor price difference between 2Gb and 4Gb in the past it was well worth it to future-proof your MBA and I expect it to be the same with the new MBA'11.
Because I bought the maxed out MBA'10 I don't need a MBA'11, my MBA will last at least until the MBA'12 arrives, at which point I might be seduced into buying the MBA'12, but most likely not needing it. So for me it was worth spending an extra €190 for a faster CPU and 4Gb of memory as it makes my laptop last at least another year, perhaps even two, longer.
So to answer the topics question: yes, it might be worth it to max-out your MBA'11 if you use it more heavily and you want to future proof your MBA. But if you're just after a light weight computer for light weight tasks, (some mail, safari, a little game, word and some video-watching) then it might not be worth it.
You're just running an inefficient setup. Why would you need to run 2 XP VMs at the same time? With a single VM and and the tasks you're describing 4GB is enough. Hell with 2GB you can do a lot as well. If the new base model Air is going to start with 4GB then that will be sufficient for futureproofing for most users guaranteed. For example, I dual boot Windows 7 on my base Macbook Air 11" (2GB RAM) and I can play Black Ops, Portal 2, etc. at decent settings. I'm getting bottlenecked by the GPU and CPU but not so much the RAM.