Generally in modern sci-fi and fantasy the proportionality of the weaponry and stakes are way off.
Take Star Wars TFA for example. At the start they fire one laser beam and destroy an entire solar system.
They don't conquer their enemies, they simply wipe them out. In Avengers, well, half of all living creatures are destroyed.
When CG armies clash literally hundreds die in every frame.
Game of Thrones fell victim to this as well once they got their higher budgets.
The entire Dothraki cavalry was wiped out in less than a minute and then respawned the next episode in bigger numbers.
The dragon had to be this really powerful thing because they had already fought a million of zombies and they somehow had to 'top' that with a new threat.