I'd highly recommend the Product Bakery podcast as set of great resources for learning more about how to develop great user interview/research skills, whether you work in Product or in design/development more directly.
I discovered the podcast after landing on Christian Strunk's blog (one of the hosts) and it's greatly improved my Product skills and mindset.
https://anchor.fm/product-bakery
https://www.christianstrunk.com/blog
(I am in no way affiliated with the podcast and/or blog other than having found it very valuable).
For me, little annoyances really stack up and make the whole experience a pain. I prefer to not have a specific feature at all, but have a great experience on what works, that keep finding little things that annoy me
from your writing, it was very clear that design was your priority, whatever other skills you might also possess. so I feel a bit vindicated seeing your username.
Also relevant: beyond IQ and EQ is the concept of "CQ" or Cultural intelligence, which is even closer to the skillset you describe.
The caveat is that the author in this case is not that different from his users, who are other devs. He gets their experiences. The magic trick for dev is putting yourself in your user's experience when they really don't think like you. Non technical, kids, accountants, whatever. You really have to drop your assumptions and forget your investments and just see things the way they do. Empathy rules, but I feel it is hard to codify that as a skill. There's a big leap before tiny wins.
EDIT- to add, the signals to look at first are user complaints, and user's efficiency on tasks with your product, aka usability studies. Empathy informs your takeways from that.