Saying Joomla development is a trivial task would be a lie. You'll agree to that as soon as you recognize Joomla as a huge PHP Application Framework. And it of course always takes some time to get used to a framework like that. Incidentally that's the situation for all frameworks of this kind, whether it's Drupal, the Zend Framework or whatever software you like. So it's not just a Joomla property and no reason to choose another framework at all.