(comp (transducer map inc) (transducer filter even?))
Of course, it's more typing and doesn't look as nice as single-arity map, but it goes along quite well with (partial map inc).
I can be wrong but to this date Clojure didn't have a function that produces completely different things based on arity, did it?
There is no reason the exact same name should be used for two different things. It is a lot harder to tell the difference between (map inc) and (map inc xs) then it is to tell the difference between (transducer-map inc) and (map inc xs).