If they made the raid rings crit/det they'd just put the atrocious substats on the tome ring and then you don't even have the choice of wearing a ring that doesn't suck. I'd rather wear an unaugmented tome ring than tenacity/skillspeed, couldn't care less about the 10 ilvl.

...actually I just want to go back to wearing pentamelded crafted rings for the entire raid tier again, bring back primary stat melds lol.