This recent question (among others) is reminiscent of a game-rec question, in that it produces a list of subjective + localized answers. Similarly, these questions seem to be the "Is there a game where I can eat my shoes and enjoy it too?" equivalent for mod-recs.
Should we continue to allow these mod suggestion questions now that we have a site policy against recommendations? Why or why not?
I think the answer is that it depends - on whether it's a question about how to change/extend the gameplay or whether it's a question about solving a specific set of problems. Asking "can anyone recommend a mod for game X" is very, very close to a game-rec and should be treated the same way. Asking "is there a mod which solves bug X", however, should be on-topic - yes, it can turn into a list if there's more than one mod that answers the question, but still it's a concrete problem with definite, non-subjective solutions.
What remains are questions in-between, such as "is there a mod which adds feature X to the game". On the one hand it's a bit close to a game-rec - asking about what mods fulfill a certain set of features is like asking what games fulfills a certain set of features, which we don't allow. On the other hand, it's very close to the question "is there a way to allow X in the game, maybe through mods?", which should be on-topic in my opinion. So I'd say these questions should remain open, but carefully scrutinized to make sure X is something concrete.
In other words, "is there a way to add a crosshair to my FPS, maybe through a mod" is legitimate; "is there a way to add more teamwork to my game through a mod" isn't.
There's a point here that there's multiple definitions for "mod". The kind of mod that basically transforms gameplay to a new game (like the Doom one) is just asking for a new game, even if it is asking for a specific game. This falls in the category of game recommendations.
So what about mods that simply alter gameplay?
The recent Morrowind example you gave boils down to a very vague problem at its core. "I want a better experience". But what defines this? We don't - that's a subjective and argumentative point, that's why we don't cover general questions of "what is the best X". This has been policy even before our game rec policy was in place. This also affects a couple of your other examples, but not all. So let's get to listing mods in general.
Questions shouldn't ask for lists of things, whether it's for a video game or not. We've highlighted all the reasons why these lists are bad in the past - high maintenance that never gets done, poor quality turnout, scale problems, and values dissonance. Let's not get sidetracked on that for now.
Rather, one should try to ask about how to solve a problem or address a concern. As with how this plays out on many other sites, applicable mods and utilities will naturally arrive in the form of answers. These will actually provide conclusion to the question, and that's what helps them become acceptable. Consider how gameplay recording went - the appearance is like a list, but the key component is that it still isn't a list. FRAPS, the top voted answer, concludes the question.
So, in a way, I agree with Oak's middle paragraph - it depends on how concretely defined the problem/concern to be solved/addressed is. And the examples he uses at the end work for me, too. If it's something that can be defined easily (group quests by zone, add a crosshair), then it is acceptable. If it is difficult or subjective to define ("improved" graphics, "add more teamwork"), then it is not really acceptable.
I closed the list because it's essentially a recommendation and, as Grace notes, we have no satisfying technical way to accomodate them.
Feel free to comment linking to your mod database of choice, maybe calling out a couple of examples.
Remember, real questions have answers, not items or ideas or opinions.
