The problem is if your moral compass does prevent you from taking advantage of tax breaks, you're suddenly disadvantaged against those who do thus leading to pretty much any pragmatist to reconsider.
Given game theory logic, I'll pretty much abuse any loopholes I think I can, but that doesn't mean I don't think we should change the rules of the game.
And that's why we can't have nice things. Yes, if you refrain from defecting, you lose to others. That's why it's in everyone's best interest to severly punish anyone who games the system. That's why society developed customs and laws against theft and murder.
The "if it's legal, it's ok, morality be damned" attitude is antisocial - it's a danger to civilized world. Therefore everyone who wants to follow their moral code or at least likes civilization should not only refrain from abusing the rules, but actively shun people who game them. Cooperation is a superior solution, but a one that is unstable by itself and needs maintenance (i.e. enforcing the rules and setting up the expectation that defectors will be penalized).
People already do follow their own moral codes. However, morality is subjective. What's "right" to you isn't necessarily "right" to someone else.
Additionally, it's part of human nature to act in our own self-interest. Call it antisocial if you want, but it's part of us. We're people, not ants. Trying to fight against that desire is a losing battle.
Instead, the focus should be entirely on the system itself to create such tremendous disincentives for crime/cheating/etc that it's in our self interest to follow the law (e.g. the laws against theft and murder that you pointed out).
A corporation is under a lot more societal pressure than individuals in regards to following norms and ethics. Most corporations (including Google) only exists because people choose to do business with them and they are happy with their product and price.
Google does plenty of charitable ventures that don't add any value for this reason and it makes sense.
A corporations bottom line is hurt when people have negative views of their company, product or practices. Individuals don't really have this amount of pressure. An individual can be immoral but legal and likely not lose their income. If people have a negative view of a corporation and choose not to purchase their product or use their service, the corporation suffers and therefore has an incentive to behave ethically.
The reason that Google and other companies can get away with these practices is that most people don't care enough to not use their product. They still find their value proposition attractive. The gains from the unethical behavior is less than the lost revenue from those that do care.
Personally, I am not concerned about their minimizing taxes as I believe that the government isn't a great steward of the taxes they collect and the extra revenue brought it would not have a positive effect.
Given game theory logic, I'll pretty much abuse any loopholes I think I can, but that doesn't mean I don't think we should change the rules of the game.