I'm split on the issue. On the one hand, if the criteria for a nerf is that a card is too powerful then I don't think the quest should be nerfed, as the requirements to completing the quest put you far behind in the early game (most of the time) in a meta that revolves around early pressure.
If, on the other hand, the criteria for a nerf is lack of interactivity, then I could see a reasonable argument for a nerf. That said, I have played with and against the deck a lot since release, and it can still lose the value game to some of the paladin and warrior lists around, in addition to struggling early game. It might be the case that it changes the way you need to play in a way that most people don't find fun though, so there's that to consider.
The biggest problem is probably that when laddering people don't like thinking of their deck in terms of matchups. "I have a 60/40 matchup against silence priest and a 30/70 matchup against quest rogue" kind of thinking. It seems like people prefer the idea of being 50/50 in every matchup, which I suppose is fine if that's what you want, but isn't typically how meta games in card games end up working out. Quest rogue is a deck that has very favored matchups and very unfavored matchups without much in the middle, so it feels overpowered or like you can't lose, depending.
Running into your bad matchup a bunch of times does hurt though.