You’d be surprised by how often rotations come in handy even in a rich tileset! It’s true that most tiles can’t be rotated without messing up shadows, but many flatter textures can be, and some people create cast shadows with dedicated shadow tiles that are essentially silhouettes and benefit greatly from being rotateable. Silhouette-ish tiles in general, even if not just used for shadows, often work great in rotation. Little detail tiles also often contain little enough information that they can work nicely in multiple rotations, perhaps standing in for different things.
I foolishly didn’t add rotation support to my game engine when I first started it, adding rotations later made my existing tileset so much more powerful. I only rotate a minority of my tiles, but I get a lot of mileage out of those rotations.