"Show me the money" is true, but 1 week has its benefits.
And as I see everyone much stake is used to upvote new users. If they don't interested in enough to wait a week for that, next time when they get nothing for their post they will leave, or exchange to BTC then leave, or cry a little about justice then leave.

1 week is simpler, and one could have more rewards then with a split period when a nonlinear reward curve is used. Now, at the end of the day, when a minnow's vote is starting to change the reward, the system starts the whole process again with a 30 days period that nobody uses because the votes worth nothing (those, who could fill up the shallow part of the curve have already voted as curators in the first period with a bot with perfect timings).

With one week, there is more room for the investors to act when the rewards are different from what they would want.