I think the main difference between the Hasui and Kobayashi's designs is that Kobayashi had a tendency to try and connect pieces in kind of a perfect world scenario. I think he took pride in designing things with a minimal amount of friction so it seems more subtle how it all connects together.

Seems like he'd be a real stubborn person who didn't want to potentially compromise the look of a toy with a better gripping joint for instance. Unfortunately with tolerances in manufacturing some of these designs played out better than others. For instance i think if Hasui had a hand in Rodimus, his backpack would be much more secure, or Grimlock, his waist more secure.

Hasui definitely designs them better as toys as a result, but i still have an appreciation for Kobayashi's approach as well, as he truly pushed the limits with Megatron and Rodimus in particular.