Because Japanese culture is to not fix what is not broken.
They know that their stronghold is Asia - regardless of how average the PS5 would be in terms of performance or how expensive they price it, it will still have demand. This is arrogance and complacency at best.
If Sony knows that Asia is their stronghold, they should be focusing on building sufficient stocks to meet the demand in Asia - instead of trying to penetrate the European and American market so desperately because they know that Microsoft has already killed it there with the hype of the Series S and X.
I know Sony has a lot of strong followers and supporters, I was a Sony supporter from PS1 to PS4 - I jumped ship to XBOX this year and never looked back. The One X alone is already convincing enough, now eagerly waiting for my Series X to arrive in November.
In terms of building hype, they (Sony) probably don't want to go head to head with Microsoft now, but then again, if not now, when? We are only 1 month away from the next-gen launch, the nearer to the launch day, the more the hype is going to grow stronger and by then, it will be already too late for Sony.