I think the lack of story behind it was a factor that made it difficult for fans to embrace it, especially as they were essentially new characters. (would have been better to have them as existing characters who gained drones or Minicons, similar to the Headmaster or Actionmaster plot devices).
And since the drones were non-transforming, with minimal articulation, the combiners were a bit flimsy.

I thought the concept was great, but the small size prevented better engineering of the figures and drones.