Anthem STR or BHK (PS Audio) preamp?? Thoughts

Of course it won't FIX a bad room but it will do wonders for bass reproduction, the toughest part of any room to optimize.  ARC is there to help with rooms that cannot be optimized due to space, wives, etc.  It's not a "cherry on top" tweak.  If the room is sonically optimized then the need for room correction diminishes. 

1. Room isn't treated well enough to get the maximum out of ARC yet.

Isn't the fact that the room is not well treated a greater reason to use ARC?