[epistemic status: attempt to quickly summarize how I feel about efforts to promote more diverse moral foundations, push back against cost-benefit comparisons as "utilitarianism", or split the difference between this notion of "utilitarianism" and rival approaches]
I think human value is incredibly complicated; and I don't think it's strictly about "harm/care" (to use Haidt's term), or happiness, or suffering. Indeed, I suspect a utopian society would value transhuman versions of "beauty", "sanctity", etc. that sometimes have nothing to do with optimizing anyone's subjective experience.
And yet, in everyday decision-making and applied ethics, I think the utilitarians, effective altruists, welfare-maximizers, etc. are basically always right. In deciding on an ideal initial response to COVID-19, or an ideal budget breakdown for an aid program, or anything else that affects large numbers of people, it would be unimaginably foolish to try to find a "balance" between the simple "prevent as much disability and death as you can" goal and some other moral framework.
Well, I think the world is pretty messed up. I think that noticing this makes the case for the SLLRNUETSSTAWMC view pretty trivial. (SLLRNUETSSTAWMC = "superficially looks like (reflective, non-two-boxing) utilitarianism even though strictly speaking things are way more complicated".)
Imagine that you lived in a world dominated by a bunch of political coalitions with organizing principles like "all other moral concerns should be subordinate to making everything smell as much like rancid meat as possible" and "our overriding duty is to make everything smell as much like isoamyl acetate as possible".
Imagine further that this has caused people who care about things like insecticide-treated bednets and world peace to self-identify as "oriented toward harm/care", in contrast to the people who are "oriented toward smell".
The take-away from this shouldn't be "there's nothing good or valuable about making things smell nicer". The take-away should be "the people who agitate about smell in today's world are largely optimizing for totally the wrong smells, and their level of concern for smell is radically out of step with what's actually going on in the world". So out of step, in fact, that if you literally just completely ignore smell in all your altruistic activities (at least until after we've ended disease, warfare, hunger, etc.), you'll do way, way better at improving the future than if you tried to optimize some compromise between the coalitions' views.
Or, to quote from Feeling Moral (critiquing those who base humanitarian decisions on "which option feels more just and righteous and pure" rather than "which option actually helps others the most"):
You know what? This isn’t about your feelings. A human life, with all its joys and all its pains, adding up over the course of decades, is worth far more than your brain’s feelings of comfort or discomfort with a plan. Does computing the expected utility feel too cold-blooded for your taste? Well, that feeling isn’t even a feather in the scales, when a life is at stake. Just shut up and multiply.
And, from The "Intuitions" Behind "Utilitarianism":
I don't say that morality should always be simple. I've already said that the meaning of music is more than happiness alone, more than just a pleasure center lighting up. I would rather see music composed by people than by nonsentient machine learning algorithms, so that someone should have the joy of composition; I care about the journey, as well as the destination. And I am ready to hear if you tell me that the value of music is deeper, and involves more complications, than I realize - that the valuation of this one event is more complex than I know.
But that's for one event. When it comes to multiplying by quantities and probabilities, complication is to be avoided - at least if you care more about the destination than the journey. When you've reflected on enough intuitions, and corrected enough absurdities, you start to see a common denominator, a meta-principle at work, which one might phrase as "Shut up and multiply."
Where music is concerned, I care about the journey.
When lives are at stake, I shut up and multiply.
It is more important that lives be saved, than that we conform to any particular ritual in saving them. And the optimal path to that destination is governed by laws that are simple, because they are math.
Or: there's a difference between cognitive operations that feel affectively "cold", versus acting in ways that are actually "cold-blooded". If your child is dying of cancer and you're staying up late night after night googling research papers to try to figure out how to save their life, the process may not feel as vital and alive as fighting off a hungry lion to save your child, but... who cares how vital and alive it feels?
I'll care about that stuff after the world's immediate catastrophes have been solved. And during my off hours, when I'm actually listening to music.