Once Upon A Time In Wonderland has its origins in a cool and eminently sustainable idea: take the Once Upon A Time mythos and tell other stories that have happened in its universe that just don’t fit into the main OUAT story. To reference a similar project, it could have been to Once Upon A Time what Paradox Space plans to be for Homestuck. As Once Upon A Time seems to include, at this point, the entirety of classic speculative fiction within its parameters (as the inclusion of characters like Peter Pan, Dr. Frankenstein, and Robin Hood suggests), if the Wonderland spinoff had been successful, this could have been a launching point for a whole network of derivative series.
Unfortunately, we instead got the most boring, bland, and tropey mess I’ve seen since that one Agents of S.H.I.E.L.D. episode. (You know the one.)