When justifying a change which is to be called a reform, it is especially important that the reason, the principles behind, the reform be carefully considered.
It is not enough to get the change through by any argument, by any means, using whatever it takes - because the world does not stop but continues to develop; and if the reform is for the wrong reasons, then these wrong reasons will (sooner or later) bend back and bite you.
Slavery was abolished on the basis that slavery was evil.
Therefore it was abolished by use of extreme force and without any consideration for the well being of the ex-slave populations after abolition - they were assumed to be better-off by definition.
More importantly, by abolishing slavery on the basis that slavery was evil, all slave holding societies in human history were then condemned as evil; which had the implication that modern society, modern people, you and me are all defined as essentially superior to everybody that lived through recorded history and up to the point of abolition.
Therefore we are not just free to discard tradition (since it is the tradition of slave holding societies) but the destruction of tradition becomes a moral imperative.
Hence modern secular Leftism; which is founded upon precisely this conviction: that destruction of the moral legacy of the past is a positive good.
If, on the other hand, slavery had been abolished because it was often cruel, and cruelty was difficult to prevent; matters would have turned-out very differently. The principle would have been established that cruelty to slaves was bad, not slavery as such, and society would proceed on that basis - presumably by some kind of laws against cruel treatment, maybe inspections. These anti-cruelty inspections would presumably spread and become applied to other social situations than slavery.
Or if slavery might be attacked in the basis that it made the slave's Christian practice conditional upon the Master's whim - in which case there would perhaps be imposed mandatory and public Christian practices from which slaves were not exempted. These Christian worship laws would then, presumably, be applied to the population at large.
The point is that each different reason for 'reforming' slavery will tend to continue after they have been applied to slavery; and the tougher and longer the fight to 'reform' slavery the more likely this is.
But the point applies generally. The Church of England introduced priestesses in 1992 and was narrowly prevented from introducing priestess-bishops a couple of weeks ago.
The principle upon which this major change was introduced was that 'exclusion' of women from the clergy is an evil act of repression.
Pragmatically speaking, this visceral conviction of the evil of preventing women having these 'jobs' is what drove (and drives) the 'reformers - it is the argument that apparently 'works' most effectively in terms of ramming these changes through in bureaucratic and media debate.
The consequence of the triumph of this argument is that all previous Christians who did not have female clergy were evil and repressive - and that therefore:
1. the legacy of the Christian past and its traditions can and should be rejected; plus
2. modern 'Christians' are superior to all Christians of the past since modern 'Christians' 'include' women clergy.
You and I might look at modern liberal Christians and seen only self-indulgent apostates; but in their own estimation they are superior to all the Fathers and Saints of Christian history - in their own estimation they are superior to the Apostle Paul, to St Augustine or St Anthony of Egypt, to anyone you like to name: St Cuthbert of Lindisfarne, St Thomas Aquinas, Calvin, Luther, Wesley, CS Lewis - all of 'em!
Moderns are superior because all of these old Christians were sexist, but liberal Christians are not: the argument is sexism is evil, ergo all of previous Christians are evil and inferior, every last one - and liberal Christians are better than them.
And this consequence follows as night follows day; and leads on to further change based on the reforming principle because of the reason used to justify the 'reform' of introducing women clergy.
Ideas matter, reasons matter, principles matter - if we get them wrong, the consequences can be chronic and catastrophic.
What 'works' pragmatically, in the short term, may lead to disaster in the long term.
Doing the right thing for the wrong reason can be catastrophic; and the righter the thing, the greater the catastrophe - since the wrong principle draws force from the right action.
Thus it is that the abolition of slavery - with slavery having been argued against as an absolute evil, and therefore naturally leading to the inference that all slave holding societies (that is all historical sedentary societies) were absolutely evil - led to the rise of secular Leftist progressivism.
At the very least, abolition fuelled secular Leftism, lent it moral zeal, and made its growth exponentially rapid: (thus far) unstoppable.