There are as far as I know. E-ink screens can actually refresh pretty fast (I think 15-20fps is fairly common, but there are probably some faster out there). The drawback is that the faster you're refreshing on these displays, the worse the image quality gets over time as the screen doesn't have time to fully clear the previous image. That causes ghosting. There will be people here who I'm sure can give better explanations, but that is the gist. Such a "high" refresh rate would be fine if you wanted to watch a video in a pinch on one of those devices, but if you wanted to read manga or something, the ghosting would probably make the experience pretty bad.