My wife and I both find the original K3 fully functional and see no need to change.
I would compare it a little to eyeglasses. CR-39 plastic lenses, available since the 1940's, are fine and I have no desire to change. Newer, generally more expensive ones have some advantages -- thinner -- and disadvantages -- worse optics -- making, for me, no interest in changing.
I'm not saying progress doesn't occur. But newer isn't automatically better. The Kindle is superior to the Palm devices I previously used for eReading. I just don't see giving up something I like -- the keyboard, and the music player -- for something I don't need.
As for a light, it's just not generally needed, but we use these in the bedroom:
http://www.ikea.com/us/en/catalog/products/20315674/
I used to say that the tremendous advantage of the K3 was world-wide 3G web access for text-based sites. This is now greatly degraded due to Google dropping its old flexible mobilizer, resulting in
www.readingthenet.com no longer working. But you still can send an email, from almost everywhere, in a pinch.