`echo (goodfish)` just looks a lot cleaner to me. and as i am still using other shells some times (can't install fish on all my clients machines) the visual difference between `()` and `$()` helps to make it more obvious which shell i am currently using.

Seems like just printing a warning to stderr or something would be a reasonable behavior (or even just printing to the screen when interactive in some special way that doesn't go to stdout or stderr in order to not mess up scripts)