Great, buy me another 32GB then please</s>. People shouldn't have to have high end gaming rigs to run a sodding browser.
Mozilla (and google) are deluding themselves in thinking that their particular software is the be all and end all of a computer, and should be introduced to this strange concept called 'multitasking'.
Firefox: 1.5GB
Thunderbird: ~1GB
OS: 1GB (conservative estimate)
Various background programs: 1GB
Suddenly doesn't look so cheap.
What are you using, Windows? I'm running Ubuntu 12.04 and the "OS" (X, window manager, daemons) is certainly not even close to 1GB, more like ~100MB.
Here's a thought for developers: Next time you find yourself saying "RAM is cheap" (or any variation thereof) thwack yourself about the head multiple times with a big stick, then go rinse your mouth out with soap and water.
In any case, the number one evaluation criterion for browsers is not the RAM profile.
If performance matters that much, perhaps you should instead be asking why we are writing applications and UI in an ugly evolution of SGML.
Before you fault the Moz devs, ask yourself why we have CSS for high DPI images and why designers embed videos into website headers. Maybe your needs aren't at all times reflective of the majority. The browser serves the spec. The spec serves every case you care to imagine. Because that's what we evolved a doc format to do.
(Just imagine a parallel universe where it was instead MS Word that evolved into a facebooking client!)
Sure, Firefox, and every other program should use as much RAM as it needs. But we should be mindful of keeping that need as low as possible, at least for any program that falls into the category of "runs in a multi-program environment and probably won't be the only program running from a finite RAM pool".