Evolution of the AI.

No, in Heroes of Might and Magic IV and Heroes of Might and Magic V, even the bone dragon looks like a quite powerful fighter. Even considering that they are constantly sleeping, guarding treasures, they don't lose their form. But the beggar mega-dragon really looks like some kind of fat toad – it can't even fly. And the magic dragons in Heroes of Might and Magic IV don't look too combat-ready.
Dragons, by definition, are reptiles, in some ways primitive, in some ways wise, but definitely not aliens from space. 3DO didn't deviate from the classic concepts, unlike its successors... I won't stray from the topic – this is just my personal opinion.