You know, if another trailer did get dropped from the Direct due to the earthquake, that might explain the incredible simplicity and awkwardly slow pace of Isabelle's trailer. They could've been intentionally padding it out to fill the space so that the Direct was still the same length. With only a week to make a new trailer, of course it would be incredibly simple, with little or no CGI. And if it were filler, that would explain why Animal Crossing was announced with nothing but a working logo.
Edit: Not that I'm saying it was changed, simply that it's feasible.