Don't we want the hash rate to be less so we get more payout?
It doesn't matter as long as we can find at least few block before the difficulty change.
If the hashrate is lower - you get more, but less often.
If the hashrate is higher - you get less, but more often.
The outcome is the same and your daily reward is always ~= <your hashrate>/<network hashrate>*144*<block reward> (currently 25BTC)
While in theory and overall they may be true. With slush, it seems like we get the same amount of rounds if we are at 800 or 1000 TH/s yet the payouts are reduced by 20%