First the producers come up with the concept for the show. Then the designers start drawing up the suit, props, etc. for the producer to approve. Next the writers write the stories for the show.
At the same time, the casting for the characters start. As well as Bandai starts making the toys based on whatever designs the producers approve of.
In short the whole thing is one huge business to them. They can't think like fans, because if they do they won't be able expand on creative ideas. Thus the franchise itself would die out.