Of course, I could enter all of my bap/bur years as (approximate) years for the birth/deaths but I have hundreds of people in one tree and thousands in another so an automatic option would be much appreciated please.
Personally, Richard, I see little genealogical advantage in your suggestion when a considerable number of people in my tree were not baptised before adulthood.
A few years ago I came upon a Church of Latter Day Saints record that showed an aged adult's baptism to have been on the day of his death.
Baptism date is considered a surrogate for birth date in many genealogical programs, including the Latter-Day Saints. My suggestion is that tribalpages users would have the option to show baptism year on their tree-views if they preferred it to seeing the rather ugly ???? when birth year is not given specifically.
Burial year is obviously almost always a good surrogate for death year, whereas at the moment we also get ???? if death year is not given specifically.