How many keys has your own keyboard? Lots of! Well, would you replace it with one that has barely 4 keys? And if i was telling you that you can normally write to a word processor? Would you then exchange it? Frankly, no, i would not exchange my keyboard. Kee4 uses a patented technology named composite keystroke. A composite keystroke is performed by pressing two keys in a predefined order and then releasing them in a predefined order. It is the first keyboard that can be used to write normal and capital letters, numbers and symbols. with only 4 keys. Visit this link for more info.
i think that this method is to be used with cell phones. That is the reason why the thumb is not used. I mean, why not using the thumb? As a side button or something? Maybe because when you hold a handy, the thumb is in front of it to hod it in place and the 4 fingers behind can type. Maybe...i do not see any other obvious application.