Guide to where it is Okay to use red and blue colors on people's names
In one place, it's cool and festive. In the other, it is confusing and annoying.
edit: I think I'd actually be okay with it in chat, should Riot decide to add it there. Just not in the upper right, where it looks like everyone is dc'd and (IMO, more importantly) makes it impossible to tell who is in the room.