I was saying the same thing earlier today. Most of their products are $100-200. I like OmniGraffle but I only need to make graphics a few times a year, and free alternatives like draw.io or even Keynote often suffice.
Yeah, I feel this. I strongly believe that the "App Store economy" has taught developers to underprice their work, and that $25, $50, even $100 isn't unreasonable. But Omni's stuff... it gets steep if you're a relatively casual user, especially if you want both Mac and iOS versions.
While it's possible I'm an outlier, I can't help but wonder if a different pricing structure -- say, $49.99 for most Mac programs, $19.99 for most iOS ones, and a (gasp) subscription of $39.99 per year for upgrading to the Pro version that covered both iOS and Mac versions of the app -- would actually make them more money in the long run.
Same boat with Omni + SketchUp. I would happily pay $100, for "metered credits" to an online service. There's a big difference between using SketchUp for 40 hours total v. 40 hours a week.
That is the issue. It is not that it isn't worth $250 for the Pro version if you use it everyday, but it isn't worth it if you only use it twice a year.
I don't really know Omni or their products, but I wonder from reading some comments here that while the bottom end of their market has been eaten by cheaper/free alternatives, the pro market that will happily pay $250 for a great tool has been eaten by things like Figma with the online collaboration that has become essential for professionals.