Direct editing is not intelligent while synchronous editing in many cases (but not all) will try to maintain design intent.
The fact that it is history-free or not doesn't have anything to do with it.
But direct modeling like for example what Solid Edge used to have in the early days (and maybe still has?) of course was the base idea to develop Synchronous. Synchronous modeling is a concept by Dan Staples from Solid Edge. It's implementation in NX is however different compared to SE. NX won't lose it's history (since NX11) while SE sometimes will. But I don't know enough about SE to really comment on the differences between the two.
Synchronous is a combination of geometry, logic, and behavior. NX had direct modeling capabilities, referred to as DMX (Direct Modeling Extension), even before NX was NX; back in the UG days of Unigraphics. DMX provided direct modification of geometry. The game changed with the introduction of the logic and behaviors we now experience in synchronous technology. Finding faces related by condition and maintaining those conditions is central to synchronous.
Synchronous is independent of history vs history-free.
I use NX from far UG11 and i agree with you that the synchronous commands have improved a lot compared to the old direct modeling commands (eg. face finder and so on) and the algorithms that are underlying these commands are very sophisticated and powerful, but in addition to this, when I was at the presentation of NX6 they have talked about the history free mode as the real news of the software, it speeded up a lot the model regeneration because the BREP is 'as it is'.
There would be so much to say about synchronous or direct modeling, such as for example, that led me to design in a different way. If first these commands were used to 'hide' or 'erase' the mistakes, now I use them with well-defined design intentions.