Lack of parity is always the downside of competitive RPGs.
Either your choices make a large impact, in which case there's a huge gap between good and bad players, or that gap is narrowed by diminishing the effects of player choices. You really can't have meaningful player decisions while still having strong parity between the good and bad players.
This becomes even more of an issue when player decisions are the only way they interact with the game. At least in something like TF2, people can get more skilled at the game, but in a game like this, the only way to "get better" is make better decisions on where you spent your points and set your sliders.