How did the Jewish leaders justify:
1. Abandoning the Temple (i.e., never attempting to rebuild/substitute it)?
2. Abandoning the sacrifices specified in the Old Testament?
It seems as though a major piece of their relationship with Jehovah was tossed overboard, making Vatican II look minor. Just curious how they sold the revision.
My take on this is:
The temple was razed to the ground by the Romans (70 AD) and the Jews were physically kept out (with a few exceptions) of Jerusalem for over one hundred years.
The temple could only be built in Jerusalem - God's holy city - and nowhere else (this is part of Jewish "canon law" and mandated by the Scriptures). The Romans also obliterated (i.e. killed) the priesthood which was mainly hereditary. Without a priesthood - no sacrifices.
Temple sacrifices could only be offered in the Temple. Since the Romans destroyed the Temple and Jerusalem with it, no sacrifice to God could be performed. The synagogues dispersed throughout the world are not the Temple nor are they extensions of the Temple. Synagogues are mainly for prayer, cultural adhesion, and teaching. No sacrifices can be performed there.
The temple couldn't be rebuilt after the fall of the Roman Empire due to the fact Jerusalem has been occupied by "foreign" people until the 1940's - 1960's (1600 years). These occupiers of Jerusalem after the Romans - muslims, Christians and secular authorities - would not allow the Temple to be rebuilt. Since the muslims have claimed the site of the Temple since the 600's A.D. and have built their Grand Mosque on that very spot, the Jews today can't rebuild without starting a nuclear religious World War with the muslims and face annihilation. They would have to literally destroy the Mosque to rebuild the Temple. Think about that in today's world

.
This way of thinking is typical of following the Law by the letter - instead of by the heart - as Jews / Talmudists do today.