Oil - and that's the only reason. I often wonder in the Middle East had no oil - what would be the state of the region. I mean would it be as desperate as Africa? If you think about it - it really doesn't have all the many natural resources and prior to the discovery of oil most the region was known for camels and nomads.
Unfortunately oil has become such a large part of our lives and the oil companies so powerful that it's going to take some extraordinary thing for us to change or habits. If 9/11 and the price of oil hasn't made us aware of this - I'm not sure what else will. I do think with the new Administration (either McCain or Obama) will have a positive effect on the price of gas - unlike the Bush, neither is in bed with the oil companies.
Currently oil production is at 183 million barrels of oil. At the same time oil usage is at 185 million barrels a day. This increase in oil usage is directly linked to the emerging economies of China and India - especially China. With the recent news that OPEC is going to drill more oil - although the reality of that statement shouldn't really have a great effect on oil production. The price of oil is directly linked to oil production NOT the amount of oil being drilled.
Let me quickly explain that statement. Currently there is oil there but not the facilities to actually refine the oil into gas (and other petroleum products).
So back to your question - the Middle East produces around 60% of the world's oil. That makes the region extremely important to developed nations.
What is funny is that power the Middle East wields because of oil will ultimately be it's demise. These countries have nothing else to offer. If you've notice some of the smaller countries like UAE are trying to develop tourist attractions - they see the end will eventually coming.
Eventually alternative fuels will be used and I personally believe it's going to be the emerging markets of China and India, if they are smart, will lead the way. For instance, China is on the verge of becoming one the biggest producer of automobiles. Well, if they were smart, they would develop it's car industry to be gas efficient or help streamline building hybrids. Don't you think if the cost of hybrids were the same as normal cars - people would buy them in droves? I mean the fact US car makers have sort of looked away from producing hybrids cheaply - make it a great idea (the US car industry hasn't done anything right in the last 15 years - that's why the lost millions if not billions over that time).
Sorry for the long winded answer but like many other people around the world - I'm not fan of the Middle East. The governments in those region make a ton of money for there "kingdoms" and the elite but the regular citizens are treated like crap. The only country in the region the effectively shares the government's wealth is Kuwait - it used to be a few years back that every citizen of Kuwait was guaranteed to have there college education - no matter where it was in the world - now that is something to be admired - I know this was the case in the past - I do not know if it is still the case, but I hope so.