As much as I've been critical of Bush's (lack of) border enforcement policy, I can't bring myself to believe that he's as corrupt as you state. Rather, I agree with suppositions made by other posters: the larger battle is the WoT & Iran.
In this scenario, we can't afford to have a 2nd front in the form of an unstable country on our southern border lurching towards some sort of marxist upheaval. So we let them bleed off their population and let the US taxpayer shoulder the load.
Bush is gambling our long-term national cultural heritage against the nearer-term threat of a nuclear equipped Islamic foe. I just wish he would come out and say so instead of looking like (a) a dunce, and/or (b) a corrupt crony of business interests.
Many of our great presidents were deeply flawed like this. Teddy Roosevelt was a nincompoop when it came to business and the economy: he savaged corporations, but in the process, research has shown, he severly damaged "small businesses." Great on foreign relations and patriotism, he nevertheless stifled economic growth in his administrations.
Bush was good for two big visions: defeat the Jihadists and revive the economy. He apparently doesn't have a third in him. Ok, neither did the great god Ronald Reagan, who gave out our first amnesty, and who allowed welfare spending to rise and who allowed the federal government to grow under his watch. But he defeated the Soviets and got the economy out of the doldrums.
Presidents, like most people, can only do one or two things really well. After that, it's mush. If you don't believe me, watch me play golf some time.
Politicians deplore the collateral effect.....they know they can't control it, but they'll do anything to hedge their bets, to protect themselves from the unexpected.