It all comes down to a price point though...
500 or so for a CA
900+ for a VFC
Lets be honest... Do we really needs airsoft guns that can get run over by cars and exploded? (Most guns will work just fine after getting dunked in water, one of my team mates took a bath in what he though was a solid icy trench... Turns out it wasn't so solid, and his TM M14 went 100% Submerged, he brought it up and it kept on firing)
There isn't much in an AEG that's water sensitive, they're much more mechanical than electronic.