Figured I would bring this up since I couldn't really find much of anything on it pertaining to this with an answer from the devs. Will this ever be a thing? It doesn't bother me that much with the black bars, but having the extra width would make the game look that much better.
We're aware of the issue but don't have an immediate solution... we put a lot of time and effort into making our pixels crisp and work in the way you'd expect while still moving smoothly, and one of the benefits of this approach is we render the game the same way no matter what screen you're using then scale it up as appropriate. Unfortunately, we didn't account for ultra wide resolutions (which were even less common 2 years ago when we started this game). The obvious solution is to show more of the game, but that has more gameplay ramifications than you might think, as many things rely on the area visible to the player.
I hope to have a good solution for this in the future, as I'm personally pretty excited for ultrawide screens and would love to own one, but it's just not a top priority for us at the moment when we have many changes planned that will affect all of our players.