They aren't trying to reinvent the game; they're simply recreating it in source and expanding on it. That was the original goal with CS:S back in '03, but they kind of dropped the bomb. They ended up changing too much. The community split between the games, rather than moving entirely over to CS:S. Notice how the two are usually very close to each other in the stats page. Historically, 1.6 was way ahead, but that's changed since CS:S is now available on Mac as well. Even with that, 1.6 still has more players. It's been like that for eight years now, and Valve really haven't done anything to address that. GO stemmed from their realization of this problem. They had been neglecting the community, and this is their attempt to make amends, so to say. GO was designed to carefully capture the best elements of 1.6 and Source, seamlessly combine them, expand on them, and act as a platform that's easier for Valve to work with in the future. That's why they're being very thorough with this beta. The quality of the game, especially in comparison to the original, is questionable at the moment, but they're working on it very actively, and they're paying close attention to the community here.
It's obviously just me, but I really don't get the point of reinventing CS again, for the third time. I mean 1.6 is still played competitively, I just watched some of the IEM matches the other day and that's a massive tournament with something like $35k going to the winning team.
I played the hell of CS 1.6 and that game is still alive and kicking, so again I'm not sure why they are trying to remake it? I guess that's my question.