I really think it depends on the relationship and the guy. I never really liked going down on my ex husband. Part of it was his foreskin. Often when I went down on him he wasn't really clean and it grossed me out. He never really made an effort to make sure that wouldn't happen, so I really avoided it unless we were in the shower or something.
His attitude and what he considered dirty talk was part of it too. He liked to talk about peeing in my mouth when I was sucking him. That's just not sexy to me.
Finally was probably just his dick itself. It just wasn't that compelling. He was pretty small, with blotchy skin and I already mentioned how I didn't really like a foreskin. Add in that he treated me like crap. None of that made me want to give the man head.
With Rope on the other hand, I really enjoy it. He is clean, a gentleman and doesn't say gross things and demeaning things during sex. His cock is also beautiful, which helps a lot. Plus, with the extra length I kind of give a handjob at the same time, which is something I was already good it. He also shared his fantasy of being deepthroated, which wasn't a challenge with my ex, but is a project with him. He jokes that its good we share at least one hobby.
All in all, I think sex is all about the relationship. I am willing to expand my sexuality for someone who was willing to offer a much broader part of himself to me. (No pun intended.)