What?

You could make the same argument for joining the armed forces.

Yes Sterile! I totally understand that and feel much the same about it to be honest!

So sterile in fact that the idea of repeated listening grates with me. I love slash's post gnr work but this is just not on par for me.

Soundgarden never were and never will be mainstream faire. It doesn't matter where they chart this album will not blow up.
The chance it did have for blowing up was if it hijacked the hipster bandwagon that the likes of Jack White and the Black Keys are riding. They're too metal, it's not gonna happen.
This is an album for the hardcore fans. They probably managed to pull this off because individually, the members of Soundgarden ARE Soundgarden's most hardcore fans.
Each of them loves that band you can hear it when they play and see it in interviews, they wouldn't risk fucking it up with a mainstream sounding album, so we cannot really ask for mainstream type success.
Anyway why would you want it to go mainstream? I have memories of Chris' "Part of me" blaring at college parties a few years back. I don't want that for rowing or eyelids mouth. Those are songs I want to enjoy alone or with other people who relate to the music as I do. I don't want them as the soundtrack to a night on the tiles or my morning trip to work.
They're too fucking good for that.