I'll be honest, all I want from a web-browser is viewing forums and news sites. If I want to trawl youtube, then sure, maybe I'll fire up the god-machine... same as if I want to play a AAA game, I'll turn on one of the black multi-core monoliths that were custom made for gaming. If I want to play a flash game, I have a mobile phone that will do that and keep my hands warm at the same time.
Honestly, the class of nerd who wants a Pi isn't thinking "should I get a PC or a Pi", they're thinking "I'm getting a Pi, what can it do better than my existing stack of hardware?".
For some, the answer is "I shall dick around with registry settings and all that fun stuff I daren't risk on my $1000 PC". For some it is "I will write educational stuff that will inspire future programmers." For some it is "I will use it on the text-based internet, with all it's forums and news-sites, and cut my carbon footprint down a chunk."
I for one haven't a damn clue what I'm going to do with mine yet... but therein lies the fun.