There's a interesting filter which is Photoshop shear. What it does it allow one to shift pixels according to a curve from one end to another. There's a few filters in Krita that are rarely used (color transfer comes to mind), but they still are there. The only application for this filter is to enable artists to create interesting background that are less uniform than the wave filter, and glitch art. There's also fabric creation which of course, would aid in concept art creation. There's a few artistic purpose to this.
Do NOT enter feature requests as normal bugs! Do NOT enter feature requests in the form of "Add feature X from application Y". That is not useful and wastes our time. Do NOT enter a wish bug for every filter in Photosop. Without theses wishes, we known they exist. We're not suddenly going to add these filters because there's a wish in bugzilla...
I'll try not to do that again. At the time, I had forgotten about the wish thing.