While I agree to an extent, the problem with the 'bigger bads' like The Court of Owls or The Black Glove is that they only really have an impact if the 'big bads' have been established already, and exist within the fabric of the story. The Black Glove was particularly sinister because it threatened to destroy Batman's legacy, and the reputation of Alfred and Thomas and Martha Wayne. That was far more threatening than The Joker spiking candyfloss with arsenic, because it seemed like The Black Glove could actually destroy the mythos itself. Likewise, The Court of Owls had always been there, while Batman was effectively playing cowboys and indians with the usual rogues gallery. They were subversive because their existence proved Gotham City to be a completely different place to what we thought we knew for 70 years. But all of that only works if the mythos is 'old', and we think we have seen it all before. I don't think either would have the same impact at a point where Batman may be facing down The Penguin, Riddler et al for the first time.