That's not an elegant solution. It's kind of lame. And doesn't even pertain directly to quests.
Fortunately, I've got your solution for you. It's something I puzzled out a while ago as I too am interested in time limits on quests and other ways to make my beloved video games more sophisticated, challenging and consequential. The solution is that you alter the quest itself. You allow a certain amount of time for the simple solution to be taken. If the player dilly dallies that time away, the simple path is closed, and only the difficult path is left.
Example: say you're playing a spy type RPG. You've received intelligence that a certain contact has valuable information you need to advance the quest. However, you're also warned that you should hurry to find him, because the Big Evil Semi-Secret Society of Bad Guys (BESSSBG, "Big Bess" for short) is out to get him. If you find him within a game day, say, then you can talk to him and get the info through a simple dialogue puzzle. But if it takes you more than a day to find him, you find him dead. Then you're on your own, chump. You've got to search his house. You know the info's in there somewhere, but the tricksie developers don't give you any clue that they've hidden it in a floor safe in a closet in the dead dude's bedroom. Hell, you can even add a timer to that path too. If you search for more than a game hour, the assassin from Big Bess comes back to the house because he left his cell phone on the kitchen counter when he hit the head to relieve himself after killing the dude and before taking the long drive back to bad guy headquarters. Now you have to deal with him too.
There you have it. Problem solved. Quest is still complete-able, just harder to complete because your spy apparently doesn't take his job seriously enough to prioritize his time appropriately.