I agree with you.... with regard to FISHEYE lenses. They're pretty specialized. Fisheye lenses can be fun to use for a while, but soon the unique look of the images tends to feel repetitive. Some folks have ongoing uses for them (a friend who does a lot of airplane photography uses one frequently to take shots inside cockpits, where space is very limited). There are other uses (humorous shots is one). But for most people, fisheye are highly specialized. I had one years ago, used it a little, then eventually sold it.

But I DON'T agree with you with regard to wide angle lenses and the ultrawides (both primes and zooms, non-fisheye) such as are needed for a DX camera. Those are much more versatile, though it takes some practice to learn to use them well.

If I were in the market for a fisheye, I'd probably look at the Tokina 10-17mm because it zooms to "non-fisheye" settings too and wouldn't be as specialized as a prime fisheye.

I carry and use a 20mm (primarily for use on full frame, but also on crop at times), a 12-24mm Tokina and a Canon 10-22mm (both crop only lenses, though the 12-24 can be used to about 18mm on full frame). At least one of them is in my camera bag virtually any time I'm out shooting. They aren't lenses I use all the time (I don't do a lot of landscape or architectural shots), but they see enough use that I wouldn't want to be without.

An alternative is to use a less wide lens, take multiple shots and then assemble them into a single panorama image in post processing. Here's a rather extreme panoramic example (more than 20 shots, hand held and shot rapidly):