Don't let the perfect be the enemy of the good. I'm sure that 99% of the people who are requesting trailing comma support care about select lists. And CREATE TABLE for the rest. Yes, the SQL standard has a huge surface area of custom syntax (rather then most programming languages which have a smaller number of composable atoms), which makes adding "consistent" syntax changes a challenge, but it doesn't mean you need to boil the ocean. Just get trailing comma select lists into a version I'm likely to use in the next decade and I will love you forever!