Right now, there is a common complaint in Retribution Paladin circles that Ret burst dps is too high, while Ret sustained dps is too low. One of the major reasons this happens is that Ret can combine at least 3 strong offensive cooldowns together (and then trinkets, potions, etc.). There is a short 20-second window when the burst dps is very high indeed.
As a general rule of thumb, you always want to stack offensive cooldowns together. This is because subsequent cooldowns magnify the effect of the previous cooldowns.
As a simple example, say you do a baseline of 100 dps. Cooldown A increases damage by 20% for 10s, and Cooldown B increases damage by 30% for 10s. If we take a 20s window, we have:
Situation A: Stacking Cooldowns
[10s * 100 d/s * 1.20 * 1.30] + [10s * 100 d/s] = 1560 d + 1000 d = 2560 damageSituation B: Non-Overlapping Cooldowns
[10s * 100 d/s * 1.30] + [10s * 100 d/s * 1.20] = 1300 d + 1200 d = 2500 damage
Stacking cooldowns gives more damage. Notice that stacking cooldowns also greatly increases the burst. Situation A has a window where the player is doing 156 dps, while in Situation B, the player maxes out at 130 dps. The "burst" dps is much closer to baseline dps.
Burst damage has always been a problem in WoW, especially in PvP. Blizzard is constantly making adjustments to reduce burst. As well, it generally contributes to an "unfun" feeling of play. 10% of the time, you're a god. 90% of the time, you're weak. An opposing player that runs into that 10% buzzsaw is going to be very unhappy. On the other hand, getting stunned or otherwise prevented from acting during your 10% window is devastating to you.
Perhaps a blanket rule that an offensive cooldown cannot be used while another offensive cooldown is active would go a long way to smoothing out gameplay. This would include things like on-use trinkets and potions, which you can control, but not uncontrollable procs. You'd probably also have to exempt Bloodlust, since trying to coordinate the entire raid would probably be a little excessive. And admittedly, saving one of your cooldowns for Bloodlust is a little bit of good gameplay.
It would also ease designing offensive cooldowns. The designers wouldn't have to worry about the combination of cooldowns, they would only need to consider base rotation/damage plus cooldown. Adding new offensive cooldowns, or shortening existing cooldown timers would become less dangerous, and more predictable, than it is currently.
All in all, I think a blanket rule preventing offensive cooldowns from overlapping would go a long way to smoothing out some of the gameplay and balance problems in WoW.
1. Excepting edge cases that generally involve hitting the haste hard cap with Bloodlust.