That is not a universally agreed-upon statement.  Payout algorithms should distribute block rewards fairly and there is more than one way to do that.  Proportional has been showed to be a deeply flawed system, which is why almost no pools use it (and the ones that do are gamed by pool hoppers).

If you think the current system distributes block rewards unfairly, please explain exactly why you think that.  Use numbers.  Feel free to refer to a particular block on the pool if you like.

Practically, I have little motivation to change the payout algorithm for the following reasons:

1. I believe that other than PPS, it is the most fair to all parties (dedicated coin miners and multipool miners)
2. It would require a fair amount of coding to change, and I have other priorities
3. Any payout method that requires me to potentially keep millions of shares in the db for 10+ coins (i.e. proportional) is going to result in the need for a larger DB system and increase fees for all users.