I find Duke kinda boring outside of WAR and Robin war but I believe he has potential and want to see him succeed . The animosity following him makes me root for him more.
I believe that he is a copy of Tim and that his creator and writers haven't done him any favours in the way they handle him. He would benefit with more interaction with the rest of the family and I believe the way he's currently handled alienates him and fosters division.
I don't believe he should be done away with but I think that while pushing him they should also remember the ones who were here 1st. It seems unfair making big plans for Duke when you haven't sorted out Tim [though I believe Tynion when he says he has plans for Tim]
When people complain about the lack of other family members in the main titles most are not asking for Duke's panel time to be cut or for others to be used instead of Duke but rather for others to feature as well as Duke.
As a Damian Wayne fan I believe in giving new Characters a chance after all my favourite was a new character thrust into an already bloated family and it ended up working out. I hope the same for Duke.