Once again, that depends on what you need the extra RAM for. If you run XP Mode (or most any Windows VM), the more RAM that you can lend, the better. The VM will run more like a installed OS, if you have at least 2 to 2.5GB to spare.
Also, 64 bit VM's require 2GB to run, just as any 64 bit OS does. I tried running XP Pro 64 bit, lending 1.75GB to it, it ran like crap. If I were able to give it 2.25GB, it would probably be OK. My next notebook will have 6GB preinstalled, so this should no longer be an issue.
There's also the "future proof" option to consider, once more software writers makes more 64 bit code programs (as 32 bit ones are trashed), more RAM will be needed. Who knows what additional RAM will cost by then? I can only assume that it'll be market based, meaning that if there are more demands for it, the cost will go up, just like anything else does.
And too, I agree with you, there's always the "my thing is bigger than yours" philosophy, that's always been in place. We could debate that issue over many things. Who really needs a 10,000 square foot home, with a workout room & a spa? I don't, but some feels as though they do.
If I had the cash to spare, and the slots for it, I'd have 16GB installed RAM. But I have neither.
Cat