CapnZapp
Legend
I realized that was your point. And thank you for making it.Assassins have bigbase damage, and +10 bonus does not double up on crit. So more or less they have a half feat waste. Reduced accuracy does not get replaced with +10 damage in rogues case.
I was curious what you meant. When you talked about Sharpshooter, I assumed you were talking about a feat that gave -5/+10 and +1 Dex.
Now I realize you are indeed talking about the other side of the coin. I just needed to mental replace "GWM" as "Cleave" in my mind

Replacing -5/+10 with +1 Str or Dex (as has been suggested for GWM) sure does benefit Assassins. (And everyone else who wanted Cleave but didn't wield a greatweapon; and indeed there is no longer any reason for such a feat to be called GWM)
Not only was the previous benefit (of RAW GWM) actively harmful to them, the new feat (the GWM best renamed into "Cleave") can't be utilized much better by fighters than rogues, which all by itself considerably helps rogues to catch up in feat utilization visavi fighters (since fighters could gain the +10 part of the old GWM up to five times per round while rogues would have to struggle to gain it more than once).
Now the difference is just (half of) +1 to attacks and damage for up to four attacks. In the greater scheme of things, that's a negligible advantage.