I looked at a Kobo Glo, in person, but didn't feel the urge to jump for one. The reason is simple enough: I usually read during the day or on transit, so there are more important things to me than a front light. Cost, size, durability, and weight are the overriding considerations when it comes to selecting hardware. Software features enter the mix too: it has to support ePubs, support USB mass media, and provide a reliable reader.
If an ereader with front light met all of my quantifiable and qualitative criteria, then I would buy it. Yet it is very unlikely that I would spend an extra $20 just to have that feature over an otherwise comparable model.