Does anyone know why the Zeon launched into mass production "DOM" as a new series of space fighters?

I mean, his size and armor (basically useless against GM beam weapons) greatly limited the number of combat units on a "musai" and its primary weapon in the form of a Bazooka with 5+ charges or rare beam Bazooka was not good enough to fight against GM.

So would it not be better to alter for fighting in space "Goof Custom", which is much superior to "Zaku", but it was very similar to him in design? Simply put, Zeon was allowed to provide temporary replacement "Gelgoog" with minimal production of military vehicles and training their pilots...