That is what a pardon usually is though... He wasn't pardoned purely because we recognise the 'crime' is now acceptable and not a crime but also because of who he was... Plenty of pardons are like that including where the crime is still a crime etc... The pardons dished out by US Presidents when they leave office don't necessarily have much merit to them... some of them are simply given because the individual concerned was high profile, well connected or even in one case simply donated lots of money.
I understand this, however this pardon was issued because of the nature of the crime and societies changing attitudes to such sentences. The legislation was deemed unjust and so a pardon was granted, but that same legislation was also used to convict 49,000 other gay men including Oscar Wilde, should they not all be pardoned....or is that simply reserved for Turin.
If so, where is the justice in that?