I think it's also a case of brand cachet. When the 2008 financial crisis hit and killed cheap lending (for the time being), it was the Japanese brands that got hit hardest. Up to that point, they'd been able to work on volume sales to keep their prices lower than the Euro competition, and that paid for relentless development. This meant you generally got a better bike for less, particularly as most Euro brands were in various stages of mismanaged disrepair (Ducati, Aprilia) or still finding their feet as relatively new to market (Triumph, KTM).
After volumes dropped, prices had to rise. What the Japanese brands discovered is that the low prices of before had a negative blowback: their bikes weren't considered 'luxury' enough to justify the prices that the Euro brands could command. People would pay a premium to wear a Ducati/BMW/Triumph badge, but they wouldn't for a Yamaha, let alone a Suzuki. Even sturdy Honda, with their best-in-class engineering, build quality, and reliability, was relegated to also-ran status.
To add insult to injury, the previously mismanaged Italian brands got much better organised and were funded by deep-pocketed owners in Audi/VW and Piaggio, while KTM exploded out of just being a dirt-oriented brand and Triumph got rich selling hipster bikes to riders smart enough not to try and home brew a CB400 calamity. BMW kept on BMWing, leveraging the aspirational branding of their cars into the bike market. They also moved away from 'good but quirky' (funky front ends, weird looks, heavy and slow) into dominating the massively profitable ADV market as well as building a superbike that rendered anything Japanese 'slow' overnight.
All this has left the big four with few profitable options in Western markets. Can't go volume, can't charge as much. The only choice left is to iterate slowly, maximise tooling value, and hope that eventually cheap bikes from China make them appealing enough to be able to charge European margins. They did themselves no favours by being well behind the curve on electronic trickery, which appealed most to younger buyers. Considering Japan's reputation as technological leaders, this was ironic.
It'll be interesting to see how it evolves. CFMoto is coming fast, and may eventually push Suzuki out as the value brand. Kawasaki and Yamaha are both part of extremely diversified businesses, and I think Honda will never abandon big motorcycles as long as the car division is profitable. As much as it's not the same company since the passing of Soichiro, motorcycles are in their DNA.