Call it what you want--Vectoring, DI, DI 2: Electric Boogaloo...
No matter what you call it, it's a mechanic that makes far more sense than previous iterations of smash, from a logical physics standpoint. If you are getting pulled inward to a combo, the natural resistance to that would be to pull AWAY from said combo. Likewise, if you are thrown very far towards the direction of a blast zone, the natural resistance to that would be to pull TOWARDS the direction of said throw, or AWAY from that blast zone.
It feels like this mechanic was implemented to be better understood by the majority of gamers. "Getting combo-ed this way? Well go the opposite way! Getting flung in this direction? Well go the opposite direction!"
Does it suck for more advanced players? Well, yes, but I'm sure we'll find ways to compensate around it. Matches I've watched between ZeRo and M2K prove that either this mechanic isn't as crushing as people think, or that there are creative, aggressive plays to get around it.