If I headed a big corporation, I would optimize taxes too and at the same time, wish that the laws wouldn't allow me to do that. Why should I be the only stupid one and give my competitors advantge?

I absolutely agree with Warren Buffet on this: he uses the legal loopholes while arguing against them. I think it's the most ethical position. At first, it may seem as hypocrisy, but in fact, it's absolutely understandable and logical.