It seems that the LCD display has been deliberately optimized for clarity, speed, and battery life. (I am unfamiliar with the technology used in the other devices you mentioned.) From the MR wiki:

Introduction

TMD has developed a TFT LCD that ensures high-contrast images by incorporating a high-resolution VGA display, with 16-level grayscale, and advanced optical performance. The newly developed TFT LCD adopts a new, highly efficient reflective surface and internal reflection technology to maximize such optical performance, providing clear and crisp images, and is able to display small, well-defined characters easily. In addition, the new product has completely eliminated the need for a backlight thanks to the highly reflective optical performance, and thus enables a low power system design, one of the essential requirements for electronic dictionaries and ensures longer battery-powered operation. Furthermore, the new product provides faster display image rewriting compared to other reflective type display technologies, thus enabling displays which are more easily legible even during fast scrolling of texts or during video clips in electronic dictionaries or books.

Specifications

Display size: 5.01-inch
Resolution: 640 x 480 (160 ppi)
Display mode: Monochrome reflective display / Internal reflective display
Contrast ratio: 12:1 (no backlight)
Response time: 20 ms
Levels of gray: 16
Power consumption: 4mW (2-level grayscale), 20 mW (16-level grayscale)
Compared to the usual E Ink display, this panel has a higher contrast ratio (12:1 vs. 8:1) and also relatively low power consumption (20 mW vs. 1mW (E Ink standby) and 750 mW (E Ink active update)). Screen refresh is a lot faster (20 ms vs. 0.5-1s).