Do you have an example of a keyboard with lowercase letters where it looks good? I have never seen actual keyboards with all-lowercase labels. Maybe it can look good.Edit: I like the look of keyboards with all lowercase letters and a nice font. Really, a good font choice helps make a keyboard look nice or "fun". It isn't important from a functional standpoint (and not relevant to the topic unless ED will consider a sleek sans font), it just adds to the look. Edit edit: Screw conventions unless they give some crucial information. If lowercase letters are more accurate, and an option ED is open to, might as well go for that.
On the other hand, upper case labels are the norm and perhaps there's a reason for that.
In my experience, in most fonts, capital letters have clearer and simpler shapes than lowercase letters. For example, the letter L is unambiguous as a capital letter, but in lowercase, it's easy to confuse l with i I | 1 .