Mr. Knight shares his comments and details about how it was for him to bring Bumblebee To The Big Screen, starting with the first Paramount call to accept the project, and then all the ideas and personal vision he had with this movie. Here's an idea, since most of the robots are G1-ish (Wheeljack is closer to Transformers: Prime) why not also make Bumblebee G1? Let's get away from the Bayverse. That ship has sailed (and sunk).
I think as the sequels go on, that may happen. The only reason why Bee looks like the Bay version in this one was because of the whole prequel reboot gamble. Now that its a comfirmed prequel they can give him an actual face hopefully
Adding the G1 robots on Cybertron was a last-minute decision. When they designed Bumblebee (which was much earlier), the movie was intended to be a direct prequel to the 2007 film (it's still not entirely clear where it stands in continuity). By the time they decided to add the Cybertron sequence, it would have been too late to redesign Bumblebee. Personally, I'm hoping they keep the current face and look. I think it's a great design, and audiences reacted well to it. Adding a mouth would completely change the look. The design still bears more than a passing resemblance to G1 Bumblebee. Big feet, chubby stomach, yellow border around his chin. A mouth would be pointless, since his current face can show plenty of emotion. And the horns were always kind of silly, the antenna are more expressive, and make more sense.
I also like this Bee better. Maybe they could add a transformation that makes his mouth look normal while keeping the rest of his look intact.