You need to understand the Gulf mentality before understanding why and how they've decided to order all the shiny new 'Buses.
Much of it is to do with the 'big d*ck' factor that features highly in all aspects of life in this part of the world.
Clearly the powers that be in Abu Dhabi, stung by the astonishing growth of EK feel that their dangly bits are now inadequate. Being part of GF isn't good enough anymore, in fact GF's a bit flaccid.
The only way to get back into the big d*ck club is to set up their own airline and buy the biggest/shiniest/flashiest that they can lay their hands on. With the cash to bankroll it gushing out of the ground, they needn't worry too much about making the numbers add up.
I think overcapacity is going to be the order of the day, especially considering the nervousness of many Westerners travelling to this part of the world whilst Osama and his cohorts are still skulking around.