I love it when a vague question like "why don't I like my bark" can result in so many various, and sometimes conflicting answers!:laugh:
I have cooked plain butts (no seasoning at all) and simple ones with just salt and pepper, and both kinds had excellent bark. So I don't think rub is all of the magic in a bark (but it does some things, particularly the salt and sugar).
So, I can see both sides here...either it wasn't seasoned properly, as in too much powdery gunk and not enough salt and/or sugar that interacts with the meat, or maybe too much was caked on preventing the meat itself from being able to form a crust. Or both.
OK, back to your regular programming I suppose. I think only the OP will be able to answer his question, but only after being able to sift through all these responses.:laugh: