Timer's
Timers were added because all content in GW2 is trivially easy and it is trivially easy because there is no trinity. Everybody runs full zerk in PvE and since so many people (often 50+) are doing one event, hardly anyone is at risk of actually dying.
CD
Missed something (example) if we are going to have timers can we not have something along the lines of time is up run to take cover, big blast happens kills all not behind the cover, boss gets so much HP back for each person killed.