Some worthwhile ideas to consider in Optimizing For Feelings by the folks from The Browser Company:

When Olmstead crafted Central Park, what do you think he was optimizing for? Which metric led to Barry Jenkins’ Moonlight? What data brought the iPhone into this world? The answer is not numerical. It’s all about the feelings, opinions, experiences, and ideas of the maker themself. […]

And anything new is by nature without precedent — meaning, without data to know whether it will work or not.