I'm pretty sure the telegraphs are there to keep you from being damaged. I'm pretty sure that at least two of the seven DPS 'battle runs' in the Hall of the Novice try to drive that into every player's memory. "Orange on the ground = bad".
I'd also like to point out to tanks - tank stance is there to aggro the mob(s) as well as your no-cost-to-you AoE. There are several lessons in the Hall of the Novice that try to drive that into every player's memory.
About the only thing the Hall doesn't teach a tank: "Stop moving while the boss is up. It means the DPS will do less damage, and they'll all die if the boss throws a tank buster that only you, the tank, can survive when you dance it's attack straight into the DPS faces."