Executive pay may be small compared to the corporate balance sheet, but the level it's at allows for and encourages bad behavior.
1. The extreme disparity between CEO pay and other vital executives encourages people to backstab in order to ascend the hierarchy. So "work" for those who are in line to be CEOs is more about jockeying for position and trading favors than about building a company.
2. In addition to (1), such disparities are bad for morale, especially when the CEO is a "hired gun" instead of someone who has been part of the company for a long time.
Except in athletics, where talent is objectively measurable, the "star system" tends to piss off everyone but the stars, and let's be realistic: non-stars are 99% of people, and probably 3/4 of those who would be considered objectively the most competent.
3. When the CEO makes $500,000/year, he's drawing a good salary but still has the incentive to build a legitimately strong company for the long-term. When he has a "performance bonus" that will give him fuck-you money in 12 months if he plays his cards right, his incentives are in the short term.
4. When there are massive discrepancies in pay between the bosses and the people they are managing, the social class and lifestyle disconnects become problematic and can damage morale. This is why the best CEOs try to appear middle-class in terms of dress and work habits.
CEO pay is at such a level that it actually brings lower quality of management. This is what's truly alarming. Decades ago, when CEO pay was much lower, American companies were well-managed and produced great products like (imagine this for a second) cars that people actually wanted to buy. Now, big-company CEOs command stratospheric salaries and generally such ass. This is because executive pay is so high that it has pushed these people completely out of touch with reality.