Thinning the herd: am I dumb to sell my most valuable lens?

Hard to say what you should do as only you can decide what is the best fit. I will say that I recently went thru a similar thing. I had the Zeiss 12mm & the Fuji 23mm. I decided I wanted the speed of the 16mm so I sold the 12mm in favor of it. As good as the 12mm was, I like the 16mm better. But then I came across a deal on a hardly used 10-24mm. I must admit that I hadn't given this lens much thought in the past as I prefer primes. However, there were times I was missing the the wider focal length the 12mm had given me so I picked it up. Very glad that I did! Excellent all around performer. Were the 16mm & 23mm I had better? Yes. But I found that for as good as the 23mm was I just didn't use it that much. Looking at my past photos much like you did, I found I wasn't even using it all that much before I picked up the 10-24mm. Ad to this the fact that I also have the 35mm f2 and it became clear to me that as good as all these lenses are, I just didn't need a 10-24mm, 16mm, 23mm and a 35mm. So, I sold the 23mm and put the money towards the 90mm. An amazing lens! Now, I have what I feel are perfectly spaced primes (16mm, 35mm, & 90mm. All weather sealed to go with the X-T1) and two zooms, 10-24mm & 55-200mm. What I feel is a very complete kit. Looking at you kit I suspect you are in a similar situation. Good lenses are hard to part with. When you find a good one you like to hang on to it. But if a lens isn't seeing much use I suggest selling it in favor of gear you will use.