And that is the main point. I think everyone agrees the PS can sell big numbers worldwide without the japanese market. But the japanese game devs are still important in this gaming age, and therefore the japanese market is still important. If PS loses exclusivity to typical japanese game franchises, it starts to look very similar to Xbox. And that is probably bad for some of the classic PS fanbase.
Yep. Something to keep in mind is XBox/Playstation in Generation 7 vs. Generation 8. XBox 360 ended up with most Japanese games on it. On the other hand, Japanese devs often didn't bother with the XB1. Persona 5 released in 2016 and never made it to any XBox, for example. One big thing that differentiated PS4 from XB1 were the Japanese 3rd party games. PS3 wasn't really differentiated from XB360 in this way. Consequently, PS3 and XB360 sold about the same amount worldwide, while PS4 clearly dominated the XB1.