From a data modelling perspective, it's nice to have them. When your input/output data has unzoned datetimes, you need to model them somehow, and it's better to

From a data modelling perspective, it's nice to have them. When your input/output data has unzoned datetimes, you need to model them somehow, and it's better to have a competent implementation than something hand-rolled. I agree that you should avoid them in greenfield designs, but I don't think that's sufficient reason to exclude them from libraries.