I think I've seen something on that theme in the Treasure Vault of the Developer's Cut edition. There should be a "making of" sorta movie (there are 5, can't remember which one that is), where the developers explain, why they did cut off the ground combat from the dragon form, it was originally intended that the dragon would be able to approach enemies on the ground. It was changed for a reason. Yes, mainly that the dragon would be OP for them, but I think it was originally meant for some boss fights as well. There's still a boss fight in the dragon form when you fight Zagon, but this (optional) boss is a flying creature, not exactly what qualifies as a ground fight.
