If you used hexagonal keys instead of long rectangles, made the keys a bit smaller, arranged them in several rows but not so many columns (so they were all accessible without excessive arm reaching), staggered their heights to make pressing combinations of them as convenient as possible, split the piano into two pieces and tilted them 30–50° upward toward the center (with the idea that each hand stayed on its own side), you’d get something much more comfortable to play and more flexible as an input device. Optimizing the layout would take a considerable amount of research / feedback from musicians.

However, it is likely that some parts of the existing piano repertoire would become significantly harder to play, or at the very least everything would require dramatically different motions vs. the current piano, requiring any aspiring player to completely re-learn how to play on the new design. But in trade many new types of note combinations would become dramatically easier.

I can’t see pianists who play e.g. 18–19th century piano pieces taking this up in significant numbers, but it would be great for people developing new music.

Even the Jankó keyboard never saw any significant adoption, and that is a much less radical and more obvious improvement of the previous design. https://en.wikipedia.org/wiki/Jank%C3%B3_keyboard