I would like to see something that would give options why it should be deleted
In most cases, topic is deleted or moved because it's not compliant with the rules. Refer to your forum rules in all places, like we do. You do not need to work for the users, but users should follow your rules. If they don't follow, it's their problem.
We have no plans anymore to introduce additional big new features like this in miniBB. Upcoming release will cover some new additions, but that's all. I'm tired of fixing new bugs because of new features, and I am interested in the stable program, not full-featured.