Knowing the % of crit chance from bosses is pointless. It is low. Low enough so you shouldn't use Awareness like Foresight when you suddenly remember that you have "garbage" cooldowns, because Awareness isn't garbage and have its own good ways to be used.

Awareness is what prevent an "oh-shit" situation when your healers have to deal with a tank-buster, because while tank-busters usually can't crit, bosses will still auto-attack you right before and after a tank buster, which might put you into an unexpected and unwanted situation if those auto-attacks crits.

Basically, Awareness is what allow you to know exactly the amount of incoming damages within the next 15sec, so if you use this in a tight situation, this will lower the pressure on your healers as they won't get caught off-guard by more RNG, which is always nice. Of there might be a lot of "tight" situations but what matter is that your healers are aware of your Awareness (ha, ha).