I think it is just a question about the size of the market. I guess you know the price for the special size dynamos like SONs/Shutters full-floating axle dynamos for modern MTBs oder one-side-attached dyamos for trikes? And these markets are presumeable larger than the market for high-power-dynamos.

And it's not only the dynamo, but also the electronics for a current/voltage regulation, a buffer battery and a solution how to attach (standard?) front/rear light.
I guess that such a complete system costs 500€ or more. And there won't be many people willing to pay that.
And you should also take into account, that more and more bikes come with a huge battery which makes a dynamo obsolete.

From my minimalistic point of view, the better way would be to go for less consuming electronic devices, insted of increasing the power needs.