Yeah that may be true, but more things should be immune to charm, heck in D&D and most PNP RPG's charm isnt much of a tool, it may not work, has limited range and duration and lots of things either resist it or are immune to it, or break the effect.
I think its why I use it so infrequently. I always get it but use it like 3-5 times ( maybe less) per playthrough.
I dont think its too powerful, I think it works on too many things and a little too well.
