1. Jankò layout is a good system, easier to learn because all fingerings stay the same. All my accordions are Jankò layout, but I'm not sure I want my grandkids to learn this system. And my piano is zebra.
2. Also, we can't expect everyone to agree, because all systems have a learning curve and once you've mastered the basics of one system it may not be very interesting to start another learning curve.
3. The 5 row chromatic button accordion also has a unique fingering system that allows one to play all keys with the same fingerings, and this system is better known to accordionist, and a 3 row Jankò isn't better or worse than a 5 row chromatic button accordion.
4. Remember the videotape format war? SONY BETAMAX and PHILIPS 2000 were definitely better systems than VHS from JVC, no discussion about that. But the standard became VHS, so what's better good for? There are far too many other elements to be taken into account.
5. There are other examples about systems and their advantages all over world history. And more than 1.000 notation systems for music, but once you've learned one, why to learn another one, even if it looks or works (maybe) better or is (maybe) easier.