This is because mori is written in ClojureScript. For the most part, all mori is doing is exporting pieces of Clojure so that the native JavaScript environment can access them[1]. In Clojure, the naming convention is "foo-bar", and the cljs compiler translates that to "foo_bar".

I can't imagine changing the cljs compiler or adding a piece to mori that must be maintained is important enough for this. I'd imagine Swannodette's answer would be "you should use ClojureScript anyway" :)

[1] -- https://github.com/swannodette/mori/blob/master/src/mori.clj...