do not limit the entire blockchain because of how you intend to use it just for steemit

This is exactly my sentiment. Steem is not steemit, the steem blockchain will have hundreds of differents use case, if you limit payout to a single 7 day period there are lots of use cases that won't be practical.
The current 24h/30 days is for sure not the best but it is a lot more polyvalent, those who need quick payout can have it and those who need longer payout period can also have it.

I have the same issue with comment pool, the comment pool is basically limiting use cases to websites with a blog/comment structure, it is much better to have a standardize and simple chain. Comments are also being rewarded right now so I'm not sure why we need this..