You should! No matter what your policy is, if you have any type of fan works, I strongly urge you to post a public notice regarding your stance on transformative works.
HUH? You say?
Well, here's an example. Let's say you are someone who is a fan artist and has posted dozens of beautiful pieces of fan art. What is your stance on individuals creating fic to go with your art? Should they ask first, or does it make your heart squee every time someone links you to your art inspired fic?
If you're a ficcer, how do you feel about someone creating podfic from your works? Should they ask first, so you can review what they've done already, or are you okay with anyone podficcing your work?
Give it some thought. There is no right or wrong answer, and you aren't a bad person if you say no or "ask first."
For a much more coherent post on this subject, go read what
Akamine-Chan &
KLB have to say on the subject!