Wouldn't allowing apps defeat the purpose of having a phone like this? Allowing users to install more apps would get in the way of having a simple phone.
If you really want to control how your customers are allowed to use the thing you can put a limit like 3 or 4 apps maximum. For example I think this phone needs at least a way to read e-books but it's possibly not going to be implemented. IF there was an API I could write my own e-book reader for it.
But it would put control into the hands of the user and open up new customer bases. I love the concept, but for me this phone is entirely useless without WhatsApp: I don't think I've sent anyone an actual text since I lived in the States three years ago.