The First Generation of Dragons realized that something was wrong with them. It was in the way they were created. Thus, they prayed to the God of Dragons to allow their lives to end.
But who would willingly end their creation's life when the time for their death has not yet come?
The God of Dragons refused to end their lives despite their lack of will to continue living. He also said that he had been telling them to reproduce but they never listened so he won't listen to them as well.
The First Generation then resolved to act on it themselves. Since the God of Dragons didn't pay much attention to them anyway, they refused to listen to him as well.
After all, it was his fault that they were not interested in procreating. If he had created them with that instinct and desire to preserve their kind, they probably had a lot of children by now. It was his fault in the first place so they didn't want to be blamed for it.