I think the point of this was more to add some variety into the monotony of grinding out quests. When nothing ever changes in a quest, it gets really boring regardless of the amount of experience it gives. It has nothing to do with how many levels of rogue you have or if you are an assassin, mechanic, or thief acrobat. Personally, I'm a mechanic because I enjoy being primarily support fire. As such, I'm one of those people that can successfully disarm a trap rolling a 1. If a character is a "pure rogue", there is NO excuse for not being able to search for and disarm traps. I dont care what kind of build you are, its 3 points per level for search, disable, and spot. Considering that I get enough points per level that I can almost go into the few cross-class skills without losing out on other skills, I have no pity. If you only took 1-2 levels of rogue, odds are, it was specifically for trapping skills. Personally, I dont like the way the multi-classing works in this game. You can take 18 levels of wizard and 2 levels of rogue just to have as high of skills for traps or umd as a pure rogue. That being said, adding a few random traps to impede (not prevent) progress would make for a nice change of pace. I love the idea of having the boxes also in random locations from the floor to the ceiling for traps as well.
The other point of this wasnt so much to increase the damage of the traps but to change the animations or exactly how they trigger. If you hit a random spike trap thats set through a large portion of a long hall way but it didnt trigger until you were in the middle of it, you would be caught off guard. The point isnt to have the quests harder, but to have them have some variety within the same quest.
Another point that has been mentioned is the "need" for a "trap monkey" that this would present. It would only present this "need" on elite and only if a trap had no way to work around. I loved the idea of a teleport trap that would send the people that hit it to a completely different part of the dungeon that would eventually merge back to the main area. This could make it where the "need" for a rogue would only be to get the quest done more effeciently if the random trap is present. On the same note, random break away floors or possibly even falling debris to force you into an upper level and having to work your way down again would be interesting.