I concur - with a lot of browsers lately running on severely memory constrained systems like smartphones/tablets and lower end laptops ... currently I have 3 tabs in chrome using 300+ MB each and about 40 using 50-60 MB.
So memory right now is important. And browsers are using way too much already.
Just as an aside, the reason Chrome is using so much memory is that each tab runs in its own process. This affords some security and stability benefits (one process dies, the rest are fine), but it obviously comes with a major price. I see this as a major architectural flaw in Chrome.
I think the processes are not the main culprit. We are using way more massive DOMs and a lot of js these days. And there hasn't been solid memory optimization efforts for js VMsas far as I know. The focus was purely on speed the last few years.
Chrome's codebase also got more complex so now every new process consumes a lot more memory. It's a way of achieving concurrency, but it's not necessarily the best way in terms of memory footprint.
So memory right now is important. And browsers are using way too much already.