My analogy is very simple - that was the law then, this is the law now.
It is unreasonable to say that a law, albeit a bad law, and there is not arguing that it was a bad law, should be retrospectively changed because society's attitudes to the background of the law have changed.
The issue here is not the law itself - which was dispassionately applied as all laws should be - but the background of the formation of the law, which was rooted in bigotry and ignorance.
But that bigotry and ignorance is the result of 20-20 hindsight, from an enlightened viewpoint of 2017, when we are more understanding, liberal, and compassionate as a society, and amen to that.
But to take an emotive issue like the repression of homosexuality and bend the law to fit modern attitudes is wrong because it opens the gates to all manner of different attitudes and approaches.
There will be a list of laws a mile long that someone somewhere will judge as having been bad law, and they may well be, but they were the laws of the time, and the notion of 'pardoning' people convicted under the law of the time because we now decide that the law was bad law, is frankly unacceptable.
It says more about our need to assuage or social consciences, and try and place our modern views on past times, than the appropriateness of 'pardoning' people who were convicted under the laws passed at the time.
Bad law is not assuaged by faulty social conscious-salving - the two do not go together.