Ideally, yes; rationally, given the incentives of the concrete eco omic system they exist in, no. Managers work for higher level managers, or at the highest level for capital owners of the business, not for their employees except to the extent that the employees are also capital owners of the business.
Managers aren't union reps for their subordinates, they are agents of capital. That's, literally, their job.
It absolutely does; just because capitalist are competing for labor doesn't mean that management switches from being agents of capital to agents of labor. Valuable, contested human resources are still resources, not owners.
> Also, the top-down structure is no longer preserved within the Agile's "self-organizing teams".
One of the most frequently reported problems with Agile in practice is that the idea of empowered, self-organizing teams is, even in organizations that give lip service to Agile development given limited, effect by management. In any case, that concept applies mainly to how teams deliver on business goals, not on setting business goals, so even ideally it would not prioritize staff opinions over business goals.
Yes, I generally agree, but it goes as follows:
1. The business owners care only about achieving their business goals.
2. To achieve the business goals the owners need to have good employees.
3. To hire and retain good employees some business decisions should take into cosiderations the needs of the employees.
So even from the purely economical point of view there should be some balance between 1. and 3.
And overall your purely economical point of view seems too rigid to me. One example that comes to my mind is the cultural shift happening at Microsoft. The company made many decisions with little business sense like open sourcing many projects and providing free developer tools. But the effect is that developers like the company more. This has measurable effects like Azure success or hiring better employees. I think this is an example of a bottom-up-built success which doesn't fit your top-down viewpoint.