Blue - is your thinking here that JP II lacked awareness of the prevalence of divorce and remarriage, [he wrote FC in 1981, at age 61, 3 years into his reign] and thus, had he been more aware, he may well have taken a different position?
Probably JP II was aware, but perhaps the whole matter is best regarded as a prudential judgement. After all, it’s not a comfortable idea that right or wrong is a function of the numbers involved. If the matter is prudentially judged, its understandable that Popes may come to different conclusions, and that others may disagree, but should accept that the man in the chair makes the rules for the Church.
But the matter is made difficult because of the high bar JP II set in FC for the Church’s practice:
“However, the Church reaffirms her practice, which is based upon Sacred Scripture, of not admitting to Eucharistic Communion divorced persons who have remarried. They are unable to be admitted thereto from the fact that their state and condition of life objectively contradict that union of love between Christ and the Church which is signified and effected by the Eucharist.”
and later…
“By acting in this way, the Church professes her own fidelity to Christ and to His truth.”
AL leaves these statements (which seem more than prudential) unaddressed.