In one word: economy.
In two words: contemporary economy.
It is beneficial – if not essential – to contemporary economy to make use of these new, readily-available masses as consumers. Those very people who were once used to propel past forms of economy in a very different guise. To enslave them – along with anyone else – turning them into more consumers of goods, which this economy needs in greater and greater numbers.
How do we know that this is hypocrisy?
Because the advocates and promulgators of this new vision of society, for which all men are equal, pose no real objections to those goods – of which we are enslaved into being consumers – being manufactured in such conditions of real slavery. Conditions which we would never allow in our golden, politically correct civilisation.
This ideology cares naught about non-white people’s rights.
And it cares about their feelings only in so far as they feel accepted in our society so as to become trapped in a consumeristic view of life like anyone else.
To reiterate, the switch was made to support a different type of economy. “Political correctness” was then coined as the concept to turn any different view into a social taboo.
This story is very similar to the invention of the myth that it is a supremely British virtue to be observant and tolerant of queues. This concept was invented and spread right after after WWII to prevent chaos and disorders during food distribution to the masses. It turned (almost) everyone into wanting to be seen as a proper British example by creating the fear of be ashamed for not being one.
Like Aristotle said, society is based on the power of shame. Creating social taboos is contemporary ideology at work.