Honestly, while the quality isn't great it is no worse than my girlfriends ford focus. The wrx is in the end based on a cheap economy car and you're just not going to get a high quality system. My gf has mentioned it can be loud when im on the highway but other than that no one complains.
Emailing Subaru may help, but i doubt it. The stereo sucks all around. Is a slightly better BT mic going to change everyones opinion on that?