I always browbeat my users away from created dims if at all possible. This is especially true if they’re new users.
As Agent K says in Men in Black “People are dumb, panicky dangerous animals and you know it”.
People will engage in bad modeling practices if given half a chance. Maybe less than half a chance. (The best example in this thread has been making Set Datums part of other features (locators) – or the default datums! – which then requiring all other features to be touched when moving the Datum.) It’s not their fault if they were never taught a better way, but that doesn’t excuse their insistence on continued use of bad modeling practices.
People WILL also learn what @O does. That one thing, right there, should be enough to scare the bejesus out of anyone advocating to use created dims in favor of shown dims. Once a user learns this, they WILL start using it. And, in my experience, randomly. In all the companies I’ve worked at, the rework and scrap cost so much I could likely retire off the money wasted.
All that being said, there certainly are times when it’s OK or even necessary. Merged parts (a forging model into a machining model is common) into parts may require created dims. Sheetmetal may require created dims. External References may require created dims. I’m sure there are others where it is occasionally acceptable/required to use created dims. The thing is, I’ve yet to see any example where 100% use of created dims provides only positives and no negatives. Fact is, in my experience, the benefits of heavily skewing toward driven dims far, far outweighs the benefits of created dims.