In your opinion, what are the benefits of adhering to canon? What creative potential exists in jumping off from it? Where has Star Trek (or other similar franchises) done it well or poorly?
The benefits of adhering to canon are that it makes it easier for different parts of the “universe” to be generated at the same time and still make sense together. It also gives an element of familiarity for new stories and you know how certain things are supposed to work.
I suppose by “jumping off from it” the question is talking about moving away from canon, like with the Kelvin timeline. The “what if-ery” of whether things would be the same if one decision was changed – so we can see that the Kelvin timeline has a more heavily militarised Starfleet than the Prime timeline. Also, this kind of contrast is seen in Mirror Universe episodes; although those have their own kind of canon too.
Star Trek has done this glaringly badly in the Trek film which shall not be named – the approach to Khan and the events of Wrath of Khan in this new interpretation come across as feeling extremely empty. Partly I think because we don’t really see much of the crew together becoming friends – in the TV series we got hours and hours of watching them work and socialise together. The original cast films had the benefit of being made a whole ten years after the TV series aired and the visibly older crew made it easier for us to imagine that they had spent that ten years continuing their adventures together, though out of our sight. Additionally, Wrath of Khan, like all of the earlier Star Trek films, had a clear message/theme – getting older, dealing with the consequences of your actions and family. Unfortunately the Trek film which shall not be named doesn’t have any kind of theme really – it’s just an action film, trying to hit emotional beats that were hit before but sadly missing them.