Reasons for Restriction of Tridentine Rite post Vatican II

If I understand correctly, the Second Vatican Council ordered the revision of the liturgical books based on the constitution Sacrosanctum Concilium. These revisions where carried out in the years after the council and implemented in 1969/70. Even during the council and even more up to the implementation of the revised books there was plenty of criticism of the council as a whole, specific teachings in particular and of the liturgy and the upcoming liturgical reform. If my research is correct, in 1974 the congregation for divine worship announced that no more permissions would be given to those who intended to celebrate the liturgy according to the pre-vatican formulae. This situation eventually led to the founding of SSPX and the schismatic consecration of four bishops by Marcel Lefebvre. Later on the restrictions on the use of the older liturgy where loosened until Benecit XVI made access to the now called extraordinary form widely an mostly unrestrictedly availably. This leads me to the following two questions: 1. What reasons where there to heavily restrict access to the old liturgy after the council? 2. Was it expected that these restrictions might give further rise to the SSPX-schism (or similar problems within the church)?