Sparano gave a thoughtful answer: essentially he didn't see the need for it now. When he first rolled it out he didn't have a lot of talent, and he wanted to find a way to get both Ricky and Ronnie on the field with a chance to get the ball in their hands. And now there's more talent, and therefore not the need.
And here's where this gets interesting. Yes, the Dolphins are now employing a more aggressive offense, and there would generally seem to be more talent now than there was 3 years ago. But is it better? After today's game, I'm not sold. There is probably more overall talent, but I am not seeing better players. And certainly, there are some opportunities (to use a euphamism).
Oh and by the way, they did run a wildcat-esque play today with an unbalanced line, and a pull into that line with a handoff to Thomas. Chad was still the QB, so maybe it fits the personnel package better - but maybe they need more of that and not less of it?