No. We had no kids and there was no point in staying in contact. We've both remarried and have not seen each other since our divorce in the mid 90s.
As for people who remain friends with exes whether they have children or not I don't believe there really is a "right" or "wrong". We're all entitled to (choose our own) friends, lovers, and spouse.
The biggest issue usually arises when their new "significant others" or "spouses" don't like it. They too are entitled to like or dislike whatever their mate does. However instead of one person trying to convince the other to (change) their mind they'd be better off finding other people who (naturally agree) with them. This is not a case of right or wrong but rather (agree or disagree).
If it's a "deal breaker" then move on!
You have to be able to love and accept people for who they (are) with whatever "perceived baggage" they may bring with them.
There are only two ways to experience joy and peace of mind in relationships: we either get what we want or we learn to be happy with what we have.
One man's opinion! :-)