What are the arguments for insensitivity? I'm not used to it, and it seems to my rookie eyes that it only opens venues for confusion (forcing to pay closer attention to symbols to mentally "de duplicate" them), inconsistencies within a same/foreign code base that make joining a project/jumping into an external library just slightly harder, and more vim/emacs/tab/spaces jihads.
The main advantage is that you can follow a consistent style in your codebase even if your dependencies follow a different style, so you don't have a situation like in Python where if you use the unittest module, you're forced into not following PEP8.
There is trade offs to both sensitivity and insensitivity. Just because you are used to one approach from your favorite programming language does not mean the other way is "wrong".
Want a consistent style? Use that nice --styleCheck:usages option. No problem at all.
Honestly, I think Nim should keep the current approach just to filter out certain people.