My opposition to this is two fold
1. yes I like to keep it simple. Currently every player is 105% of real life PA, one formula for everyone. I don't wish to have to look up each individual player and determine which formula to apply.

That is the opinion of the guy that puts a stupid amount of time into this stuff already but that's my minority opposition, my majority opposition is

2. I hate lazy apathetic GMs. There are hundreds, maybe thousands of leagues out there that have 120% round ups, unlimited usage on bad players, oversized rosters, etc. and those leagues suck, you don't even have to try to field a team. This is the one league that has very challenging rules and, even though many push the limits, you must be engaged in this league because it's challenging to field a team much less win on a consistent basis. I have no desire to make rules to make GMs be less engaged and try less than they already do.