I put the blame for this disparity squarely on the non-optimisers. Clearly they aren't serious enough about the game.
So you have to optimize in order to be serious about the game? Some people like the concept of their characters more than just the numbers. There are some powers that go more with the concept of one's character while not being the best choice due to the numbers.
This is a problem in my opinion because it makes some think that they are only supposed to create characters that are the best which leaves you with the same builds every time you play. That is not what this or any RPG should be all about.