I think sly is more clever than arnold movie wise.
Arnold's movies are all the same basicly, just like steven seagal's and vanadamme's, but because of his social status and charisma he made the most money in all of hollywood history from movies alone. I mean he is a god afterall.
Sly in the other hand would've dropped in the steven seagal fail trap if he did the same shit in every movie, people wouldn't have cared for sly anymore. But Sly allways kept up with the times and was willing to take note of current policy's, thought processes, politics and everything. He is a movie genius and knows people and knows how to produce gold himself so he's a self taught man prety much.
I think people are realising that they can't make new movies anymore. Every topic in the book has been beaten to death and people want to go back few years when a movie came up and it was "new" and "special" so why not make an oldschool action film with cheesy one liners to take people back in time.