I don't know if it holds for every scenario, but when it comes to microtransactions or DLC, I judge from the rule: Is this just bitflipping?
If they want me to pay for simply giving me a higher value of X resources, it's bad.
If they want me to pay for adding new content to the game, that's fine.
There is a grey area when it becomes apparent that they removed key content from the "full game" in order to charge extra for it. The new Battlefront 2 debacle shows that.
This should also cover the cases of user added mods since making your own content or hacking your copy of the game would be fine.
If they want me to pay for simply giving me a higher value of X resources, it's bad.
If they want me to pay for adding new content to the game, that's fine.
There is a grey area when it becomes apparent that they removed key content from the "full game" in order to charge extra for it. The new Battlefront 2 debacle shows that.
This should also cover the cases of user added mods since making your own content or hacking your copy of the game would be fine.