I tend to prepare a lot of environment and a lot of plot. But the plot is designed in such a way that the players are able to alter it.
So if the players ignore what I planned for them, and negate a situation by being clever (or blunt), that's fantastic. I've never been in a situation where the players did something I didn't expect, and I didn't like it. The trick is to not 'intend' for the players to do anything. They can do whatever they want. If they say "screw the riddle, lets kill that thing", then more power to them.
I gave XP, but I needed to comment about how much I agree. As a DM, we have the whole world as our playground except for a few individuals - the PCs. Let the players take them in the directions they want, and explore the consequences (good and otherwise) of what it means in the world. Don't be so attached to an outcome or plot direction that you overrule your players and railroad them down the path you envisioned.
While I try to live this as a DM, one of the best examples comes when I was a player. Campaign started with all the PCs getting press-ganged into working for a pirate who has the only skyship in a several country radius (playing FR, this was before Eberron was a thing - AD&D 2ed). DM had a whole campaign planned of us as pirates were we up for. Anyway, first session the Captain was impressing on all of us why he was captain and the rules of the ship, and I forget the actual sequence but one PC ended up in a duel with the captain. The captain was a high level NPC with magic items, it was a forgone conclusion he'd knock out the PC and show he was boss. Except that the DM had introduced a crit chart from somewhere and let us know about it before the stat of play.
Second round of combat the PC scored a crit, rolls happened, and he ended up cutting off the captain's leg. And then finished him off.
The PC immediately let on that the recent people press-ganged (our PCs) were a powerful adventuring guild (you needed a charter in FR back then) and none of the pirates should mess with us, and he was the new captain.
The whole planned campaign just took a flip. DM loved it and jut ran with it. We were a bunch of 1st level PCs who couldn't show weakness in front of the pirates, deal with all the bounty hunters and stuff coming after the pirate captain (now us), had an airship and a bunch of magic items well above our level that others desired and sent people trying to steal.
Ended up being a very unique campaign while it lasted, and it never would have got there if the DM wasn't willing to literally discard every plan he had made and just go with what the players did.