Yeah this was rather experimental on our (Events Team) part. We clearly have to appeal to more than just the try-hards, so I really didn't like the idea of single elimination from the start. I'll also agree that it does seem a bit odd to have 5 weeks of matches to only drop 7 teams, but due to math (how things line up) there isn't much else you can do. We could give the top 4 performing teams a pass for the first week (why play in a tournament if you don't actually get to play matches?), and only move on 12 teams (thus the first two weeks of the knockout stage would consist of 8 teams, which wouldn't really change the duration of the tournament.
What I've thought about for future tournaments, is to give say, 3 weeks for the teams at the group stage to schedule and play all of their matches, rather than doing 1 match a week.