Not so; you're still as good at this as you were. You've said that you're going for a story that's accessible to people who don't know the source material and you've very much succeeded - I have never played a Mass Effect game or Skyrim because my computer would try and run it for three seconds before giving up in a shower of sparks and a noise like the suicide of a euphonium, and I'm having a wonderful time with it. Additional familiarity with the source material just allows one to pick up on more of the character nuances and enhances the experience slightly.

tl;dr: Don't beat yourself up about not everyone sharing the reference pool, for that way madness lies.

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"Yeah, I'm definitely going to hell/But I'll have all the best stories to tell" -- Frank Turner, The Ballad of Me and My Friends

As an aside, the alternative to liking a story more when you know about the source material would appear to be liking it less when you know about the source material, and that really doesn't bear thinking about. =]