I don’t think Reagan loved amnesty. I think he gave in on a couple of issues in order to get what he wanted done on others, and this was one of them.
The deal was, that if amnesty was extended to the illegals who were already settled in the country (far fewer than now), then that would be the end of it, and no more amnesties would be extended.
Of course, the Democrats were lying through their teeth about that, and Reagan should have known better to trust them on anything. Perhaps he did, but thought that defeating the Soviet Union or lowering taxes by 30% across the board were more important.
Anyway, as I think Sarah understands, the whole business was a clear warning to conservatives never to do it again.
After he was out of office, RR admitted his amnesty was a mistake. I am certain were he alive today he would not support immigration reform in its current form.