I know many people are thrilling with all the freedom D&D Next issue to the DM, and many people are hating it for the same reason.
Myself, I sit with the "hate it" group, but not because I want CharOp to become the norm to the new edition. It's because rules-light systems tends to make two tables running the same game too much different from each other. This removes the sense of unity that playing under the same system brings to the community.
When you have a set of rules to backup your playing histories, you give to the community a sense of "wow, I can do this in my table too, and my friends will see the awesome". Sure, many classic tales do not involve rules at all, like the dreaded gazeebo or the Head of Vecna. Also, it's not a coincidence that both histories are comical in nature. Jokes are easy to catch up. Sometimes they use special words, like spherical chickens, but if you know the jargon used, you laugh.
This is kinda harder with heroic prowness. Sure, everyone know a tale about how a follower killed the dragon with a 1d4 dagger after the heroes weakened it, or how the DM allowed you to develop a booby trap using rope, syrup, caltrops, and a celestial dire badger to terminate an encounter defeating all the orcs when they tried to charge your group. But both histories lost they shine the instant someone asks "how you did it", and the answer is by sheer luck (dragon), or DM call out of the guidelines (non-standard trap).
The problem is when you player start to stock with syrup, in the hope to use that trap everytime against every encounter. Then your previous rule become a precedent, and the player will be upset when you say to him "no, because I said so". If the situation is REALLY unique, the chance of it's appearing later to bite you in the back is lower, so, DM ruling is fine for it. If the situation is possible to be repeated at will, or at least once per session (lets say, the fighter asking to swing hard and hit 3 enemies at once with disadvantage against all), don't be mad when the player want to try it every time he faces that common situation. For these, rules are better than ruling.
I talked to much. Just wanted to give this food for thought.