You could get some epic battles in that era. Even if people can't fly yet, they can leap 30 metres into the air, move at the speed of sound, throw punches that crack mountains and fire spectacular ki blasts. Goku fighting Yamcha, Goku fighting Tao Pai Pai and battles with General Blue who uses telekinesis could all feel epic and action-packed if this stuff was used properly.
Those battles would make for fun battles that take place during the movie but would be pretty unsatisfying for a final climactic battle. Most of the fans who would go see the movie wouldn't even know who Tao and General Blue were. They weren't really that memorable as characters or were even that great a fight scene.
I'd hardly even call his confrontation with Blue a fight scene. The Red Ribbon army wouldn't make for a good film and it wouldn't have what people would expect from a Dragon Ball.
The villains are named Commander Red, Colonol Silver, General Blue, Captain Yellow, it sounds like something from Captain Scarlet. In other movies you'd have villains who wanna take over or destroy the Earth or rule the universe but here you'd have the midget from Game of Thrones commanding a huge army with the goal of getting a wish to be tall? It'd be stupid as a movie.
What if Dr Gero was the main villain, pulling the strings of the Red Ribbon Army?
They'd need Gero if they were to ever get as far as Cell but they could easily rework Gero's origin so he wasn't tied to the RRA. Make him a genius with mental issues he develops an obsession and jealousy with Goku over his power and ability to fly. So if he isn't able to do such a thing he'll create a being that will be even better, perfect, so Cell is created.
Though instead of Cell wanting to kill Goku because he was programmed to he decides to do it of his own free will to prove himself, like Goku but without the good intention.





