This is a good question. Is "originality important"?
-No
Why: because its how your players deal with whats presented that creates the "originality".
Never loose sight that it is the players themselves that write the story, you...the GM...only supply the ink and paper and a few bare bone facts ("your in a village on the edge of a forest, locals say there's a hidden temple at its center" period. What do you want to do?
If your players start getting bored its probably not the lack of originality (as in have they seen this or that trick or trap before) but rather they're detecting routine (say going into a crypt 20 times in a row). I disagree with a few of the above posters, however, about making copying really obvious. This is "tounge and cheek" and purposely reminding players of other modules may be funny, but will remind them they're only playing a game, remind them how they handled this or that problem before, and start to muddle the two gaming experiances. Chances are, players won't remember or even care if you reuse the same old stuff, because they are focusing on other things (the setting, their PCs personality, the new random encounters they have etc.). AS GM NEVER assume your players even care about "originalty". Most don't. Just mix it up a bit. It's like your a chief with only ground beef to cook with, make: hamburger one night, meat balls the next, then sloppy joes etc.
Infact, when it comes to modules, I am a big "anti-original idea" guy. When people start evaluating if a dungeon was good or not based on how many novel tricks or traps it has, or interesting situations, there missing the point of the game IMO. Forget about original ideas. What makes a good module is a cool setting, variety, and situations that allow each class to shine throughout the game. Also, the inability for the players to predict whats going to come next. Infact, you could have a module with zero original ideas, yet feel completely fresh. And you could have a module with 20 fantastic and original tricks and traps, but stick these in some sickly straight jacket linear story plot, or cornball setting with tons of nonsensical filler and it'll be a snoozer....and worse yet, these original ideas will look to the player to be nothing more then an attempt by the writer to cover up a rushed development/writing job with cheap gimmics. Unfortunately, many new modules are rushed out, with little thought about if there fun to play, to the writers what matters is "is my story evocative, and is it "original", as if its sold to read as a complete romance novel rather then a catalist for the DM to flesh out. I think Dragon Lance started this trend, and it continues today.