Greedy companies are greedy. Lowering to 15% won't magically make them good corporate citizens. The carrot and a really big stick are needed. I don't see this admin taking a stick to corporate America.
IIRC the Russians tried a 13% rate for a major tax and found that it worked fairly well. If you hassle enough you can get below 13% (or 15%), but hassle has its own cost.
Implying "Greedy companies are greedy" is bad makes little sense...
Greed is defined as:
> intense and selfish desire for something, especially wealth, power, or food.
I've never met a person who wasn't greedy, seriously even a pastor has the intense desire for followers.
Further, it's literally only possible for a company to exist if it is greedy. How else will they pay their employees, investors, etc?
Now, we can argue some companies are "excessively greedy". However, I think that's still probably not the correct way to describe companies that shaft their employees for the bottom line. By definition being "greedy" implies "intense" or "excessive", I think a better term would be "short sighted".
A company which harms it's employees, customers, etc. and tries to get the most value is "greedy" (just as all companies are), but what makes it "bad" is the poor management.
I think the whole point of this new proposed system (aka 15% tax), is that it tips the pro's vs con's list of companies keeping money here to "pro". That's how economies work.