It’s not really Vista’s fault, most 64-bit OSs (including linux) have swollen memory pointers and allocation problems. It’s just a by-product of having the extra bus size and addressing capabilities. Larger files in memory also clogs up the processor’s cache but since that’s increasing as well it’s not really that big a deal.
Do most users care? Not really. They just counter this by buying 6GB instead of 4GB. The way memory is going it’s not really that expensive to buy 2GB sticks anymore.