All the Reviews of the Nook Glowlight I've read mention how the Glowlight give a more even light on the page compared to an external light. An even lighting means a better reading experience. In addition, the Glowlight allows you to read in low light which you can't do with any of the current crop of ereaders with eink.
Considering the reviews and popularity of the Nook Glowlight, Amazon would be nuts to ignore it. When it does come out, I plan to buy one. However, I'd prefer they take their time and get it right rather than rush a product to market full of untested problems.