At the very minimum a player should be able to tell who's TKing them. That's just a fundamental right for gamers, I'll be damned if I'm going to have to speculate who just shot me in the back of the head execution style.
The chat screen is almost worthless because not many people watch it and most people move around in a blob which doesn't necessitate a lot of written chat and you can't chat with the enemy team (for better or worse). Hence using it to make server announcements is not ideal for getting the word out either. That's why the only chat in there is about recruitment and TKs. During the span of an entire round on a full server you might get 10 lines of chat.