That is an excellent point. However, I would speculate that very few people would buy such a keyboard for a couple of reasons:
1. It would have to be wired. I just don’t see how a wireless keyboard even with a large battery would last long enough before having to be recharged.
2. The price would be too much to ask for many. Building in the touch bar and the fingerprint sensors (which in my opinion is the most useful feature) would add a significant cost. I would speculate that it would have to be sold for more than $300 to just break even the development and marketing costs.