Well Poison: Poison Trap and Traps: Poison Trap are rather different powers. Poison's is a hold that works as a proc monster, Traps is a -regen power that can hold (and I think most people don't realize that the 10s duration listed in the power info in game is 10s per tick of the AoE that lasts for 30s)
I can't really argue with Trip Mine getting a Cast Time reduction.
And Time Bomb has always been the worst power in the set by a wide margin, I have always skipped it and probably will always skip it.