There are far more mindless ships in the Merlin fandom so why choose the canon legend relationship as the worst offender? People ship it because they know the legend and therefore believe it's inevitable. In fact, the writers have hinted that Arthur/Gwen is a definite plan for the future so I suppose, using that logic, that the writers are stupid too? Or are we allowed only to ship it after, what you deem to be, enough interaction for a developing mutual respect and attraction has taken place? Surely part of the interest in the pairing stems from wondering how the barriers between them could break down. That's what I believe fanfic is for: exploring possibilities that the show has yet, or can't ever, show.

LOL, I don't even ship Arthur/Gwen! However, I really do think your secret is founded upon some rather strange principles...