Backlit keyboard will look nice but I can't see many use cases for it, imo. Still good news.
... only situations where there is not enough ambient light to see correctly keyboard or symbols on keyboard keys
Imagine you are in bed and you want to do somethong: you can use Pyra without turning on room light.
And think that Pyra is a really mobile pocket computer: you will use it in a lot of situations and different places, and not all of them will have a good ambient light. So backlit keyboard is a must imho. Backlit keyboard for Pyra is infinite more necessary than in a desktop keyboard.
I have a Zaurus (what and old machine) and as its keyboard does nota have light, I can't use it in a lot of situations where I would like to use it.