Could messages be graded by importance, eg 1. Stuff that's not directly happening to the PC (eg spider-spam, confused monsters), 2. Stuff that is happening to the PC (probably all those monster attacks that fail to hit or damage, maybe some other things, 3. Stuff stuff that is happening to the PC (pretty much everything else, damage taken, stats changed, poisoning, stunning, disarming, messages that result from player actions the pickpocketing). You could then the game to show all messages, grades 2+3, or just 3.
Crits should definitely be in red like stat decreases. Maybe non-attacking PC-monster interactions could have a colour too?