Mmm..I'd say that averaging games takes out chance more than skill. Since in all situations a better player will play a better play (assuming he didn't get tired, etc., etc.) and you want to give him more opportunity to get rid of that chance through more games.

About 30 minute games: well..It's only a dream (since I'm not even sure that I'll cope with those for 4-5 rounds before getting tired), but it's still some form of solution. And to mention a possible solution, Tournament in Rome is going to have something along those lines: they'll have a bunch of Swiss and after that top 16 (I think, or maybe top 8) is going to be decided by 2 out of 3, which is a middle ground between an ideal solution of a lot of games per round and just one game per round. And this one at least has some justification since in Swiss you have some averaging (if not over same deck, but at least over a few games), while in top it usually gets a bit random (which shouldn't be the case).

My lack of experience in the tournament environment poses this question:

Wouldn't shortening the duration of games favor rush decks over control/slow decks?

Assuming a purely hypothetical situation of players managing to finish each game in 30 minutes, no. If most of games will be modified wins, then probably. But I always look for the best in people and assume that at some point people will get used to playing 30 minute games.=)