I get that the regular Kindle is better for reading in sunlight, but who really does most of their book reading outdoors or on the beach? ...
... I primarily use the Kindle app and I like reading in the reverse font where the letters are white and the background is black.
Sorry for the rant, but I don't see the big deal about better reading in direct sunlight, but I'm a bed reader and not a beach reader. If I was a beach reader, then I would just get one of those $79 Kindles and just use it for that purpose only.
I realize that you were responding to a particular post and I agree that many of us are not beach readers and thus having a dedicated ereader for just that purpose has a small audience. On the other hand, I like having a dedicated ereader for other reasons.
If you read for a long time, computer screen glare (that includes the Galaxy, Kindle Fire, IPad) becomes an issue. Your suggestion of a dark background with light letters is a good one, but still, in daylight (and that can be a living room, not necessarily something outside), a dedicated ereader is more comfortable to read. (In bed, you are right. I use an ITouch with an inverse screen for that. Any of the devices mentioned are good in that they provide their own lighting. Ereaders are inferior for bedtime reading.)
Secondly, with the smaller dedicated ereaders (I have a Nook Touch), they are still small enough that I can stick one in my front pants pocket. Any bigger, then I have the problem of where do I set it down when I am at the coffee shop ordering, the dentist, etc.
Finally, I prefer Nook simply because I object to Amazon asking me to pay in order not to have advertising (the Amazon Touch) or letting them track my web browsing so that they can send me appropriate ads (the Kindle Fire - that is why it is so cheap). I don't like ads on stadium walls, in my airline seats, more spams, etc. (People love DVR's not only for being able to watch shows when they want, but in order to avoid advertising.) Why give any company the license to add more invasive advertising to my life. JMHO