2. Regarding the readings, it should not be neglected that the texts of the readings and the rest of the proper cannot easily be separated because they are one unity.
3. The propers of the Mass, particularly the readings, are also reflected in breviary. Changes in the readings would disconnect the Mass of the day and the breviary.
4. For the readings of the weekdays and feasts of saints the situation is even more complicated. The new liturgy foresees a two year cycle for the readings on the weekdays and it is even recommended to follow this cycle also on the feasts of the saints. There are readings for these feasts, but the idea is not to interrupt the continuity of the weekday readings. I cannot see how it would easily be possible to harmonize this with the former discipline.
5. The church has an universal calendar, but in addition to it there exist local calendars of each country, of each diocese of each church or of religious communities (...) and these calendars reflect the local traditions in feast days of saints that have a certain importance for a certain place or of certain particular circumstances (dedication day of a church, patron of the church, of the diocese of the cathedral, saints whose relics are in the diocese and so on, special masses to our Lady under a certain title under which she is venerated at certain place...). Therefore, there has never existed such a strong uniformity in the calendars and it is even against the "spirit of the liturgy". One look at the appendix of the Missale Romanum (edition for the liturgical use) with the local calendar for the US gives already an impression of these problems.