Yes! A thousand times this. Being able to distinguish users was the whole reason I thought up the interactions thing. There's a post of mine from ages ago with I think thenewgreen about avatars where I proposed that people should be able to add RES-like tags to people. Maybe even give it a color. Or, better, let me choose what color/font/whatevs the people I follow look like (because I might deeply hate your Gothic typeface, Klein). But yeah, just like on facebook, if I can better recognize you, I will sooner care about you and think of you as someone not like everyone else. As long as a feature is not too taxing on the servers I'm all for it.
I totally agree 100%. I think also the anonymity on cites like these makes it easier for strangers to feel no reason to be kind or caring to each other online. If they insult you its as if they just insulted a string of letters (your user name) not a real person. There where times when I would walk away from a conversation online feeling very insulted and upset making me less likely to post.