By reprogramming DME one can play Jingle Bells, flash christmas trees on the screens and manage millions of engine management parameters. There is no limit, but learning the DME first takes time.
Piggies intersept just a few signals. So they are limited in what they can do. Fast to develop for new platforms, but flashes will take over and piggies move to the following new platforms in which they have the advantage. That's why the piggyback market is so great. For the most customers, intercepting a few signals is more than enough.
Managing all the parameters in DME is a very different game from trying to make the most out of intercepting the signals. Wise men stick to the game they master. Not concentrating fully on piggyback development but trying to win two games could make them lose in both.
For a new tuner in N54, what's the point of going the piggyback route? There is a limit, and the competition is almost there already. There would be no way to be any better than the current champs.