Has it ever been compulsory?
You have to go for goal once you've indicated that you're going for goal*, otherwise it's just a kick, whether tap and go, cross field, or for touch.
* My brain is insisting that that's a rleati new thing, as in post-professionalism. But easily possible that I'm confusing "Aidan learned that" for "became law".
ETA, I'm sure I remember Arwel Thomas indicating for the posts, then tapping and going to score against England, though I accept it could have been an assumption by England, not an indication; butnthats around the timeI'm Ithinking of it being an actual commitment.