let's not forget what Marx thought was right about capitalist exploitation, for this is what is distinctive about his position! Indeed that Marx described the relation through what was then an abstruse French term shows that he was not simply condemning capitalism for its injustice or unfreedom. The negative connotations today are largely the result of Marx's usage and theory!
What's right with exploitation? Capital has been able to achieve historically unprecedented levels of exploitation through compelling the capitalization of surplus value, the development of the productive forces, the laying of the basis for a higher form of society. It's not until that basis has been laid and transition is itself compelled does Marx argue that exploitation can and should be eliminated. Unfreedom is not in itself warrant to condemn exploitation tout court.
That's just a normative critique repackaged in terms of unfreedom rather than injustice.
And is it meaningful to rank societies in terms of the achievement of freedom. Society depends on unfreedom, the question is simply which kinds are not recognized as such, whose freedom is secured at the expense of whose. We seem to need a bit more of Nietzschean/Foucauldian skepticism here.
Yet Marx was a social scientist (because he was not a nice guy, he was not a philosopher like Aristotle or Kant); he had his invisible hand theory, for he shows that in the pursuit of profit capitalists MUST create as if led by invisible hand the possibility and necessity a higher mode of production, though that can be achieved only through the visible hand of class struggle! It's the combining of invisible and visible hands which makes Marx appear a positivist and scientist.
Workers suffer vulnerability; their means of life have been appropriated from them and are personified as a capitalist who advances wages only on condition that he can himself profit from the use of the workers' labor power. This existential vulnerability also puts the capitalists in the kind of panic room in which Jodie Foster had to hide.
Constatin Pecquer, 1839:
"One fact is certain, general...it is the silent but very decisive struggle of the workers against their masters with a view to forcing the captains of industry to raise their wages...
"How can one not see that to leave [the wage earners] dependent on the insufficiency of a fluctuating wage is to wish to find oneself surrounded in times of crisis and general unemployment by a famished multitude, to create riot and civil war, and perhaps to arm new Spartans..."