I find myself disincentivised to play.
Ladder decay has introduced additional noise to ladder. Normally it's an already loose approximation of skill. Now the effect to noise ratio is so large as to be meaningless. Even if I play every day (as if I could find that many games), and remove all the noise from my own score, I still could not make inferences about my own skill relative to others due to not knowing whether their score has decayed.
There are some arguments for having decay, but 400 is far too large. Rust will never make a 400 elo difference. Maybe 100 tops, and that would be down to near nothing within 10-20 games.
DeinFreund was working on an alternative system. But that seems to not have been implemented yet?
I know elo isn't that big of a deal, but personally I like seeing whether I'm improving or not.