I don't think that's true. They are required to pursue what the shareholders deem important. That's usually profit, but sometimes there are votes to sway the company in a different direction. As a simple example of this, activist investors have spurred change in some industries that wasn't purely based on profit.[1]
Depends on shareholders, doesn't it? Those are the people that 'make up' the corp. The rest are pawns that either fall in line or end up recognizing that the only way to win the game is to not play (and thus quit).
If employees think their employer is doing something unethical, that harms morale.
If morale is harmed, good people are more likely to leave. If an employer has a poor reputation, it becomes harder to hire employees with in-demand skills.
Poor retention and difficulty in recruiting employees can end up harming the business.
Sadly there are far more workers with a broken moral compass than you'd think. Luckily, there are also enough with ethics and key positions to somewhat cancel that out, but I wouldn't say that unethical employers have a much harder time than ethical ones. It's probably simply a different spread on money/package/freedom within one such company. Plenty of people will believe what they are doing is justified and ignore any signs of cognitive dissonance if the pay check is right and internal communication is 'managed' enough by HR.
Gates has always operated at the world level. In business, he wanted nothing less than total domination. The older, kinder Gates has a philanthropic ideology that is no less bold - he's thinking big, at the global level.
Being separated from that, Microsoft is doing what they are supposed to do - be Microsoft-centered, and focus on profit. But they can be more objective, with the founder's emotions no longer driving the company's direction.
Because maybe, just maybe, they're a tad bit less evil?