This question sort of reminds me of the differences between wants and needs and knowing which is which. I would say a fetish is a need. You don't get as sexually stimulated or maybe not at all without that fetish being a part of your play time.
You may want to wear high heels because they make you sexy but you don't need to wear high heels in order to get off. Look at a fetish almost as a sexual OCD sort of thing. You must do it in order to feel satisfied.
I agree, well put. Also, "sexual OCD"....that made me giggle.....nicely worded.