Yes! Just play with filters, new in 0.46. For example, using two turbulence inputs, displacement map, and blur, I was able to get an extremely realistic "watercolor on rough paper" effect.
True, filters are slow, and take a lot of memory. But that is a problem that constantly solves itself thanks to Moore's Law. Besides, very few people really need complex or realistic textures. For most people, a simple blur is all they will ever need. And for them, the advantages of much smaller, human-readable source, scalability, easy editability and maintainability of vector art are paramount.