Maybe the problem is the tyres not being suitable for the job? Just because Bridgestone changed construction and increased warmup grip doesn't mean the construction of the tyre is ideal for things like braking and turning. Why does the chassis always have to be the problem? Why do the teams have to figure out how to handle an inferior part they are forced to use?
Right now, the current carcass doesn't respond well when carrying your braking deep into a turn. It folds over a bit and with every bump it tries to absorb, the carcass responds by trying to rebound back to its intended shape, upsetting stability.
If you get most of your braking done before the turn and carry the ideal speed through the turn, then great, the new tyres can be ridden chatter free. The problem is, the first racer into the turn usually comes out firs.t So outbraking your competitor is still paramount. None of this is a problem if you're out front with a gap and have the luxury of creating your own lines and braking points with no one to potentially interfere with your prefered line. But that isn't racing reality, is it?
What's real is that it is still quicker to brake deep through the turn up to the slowest part of the apex rather than brake down to the ideal speed before the turn and then carry on through. There's easily a 1/10 second that can be lost there. And over 15 turns, that's 1.5 seconds/lap.
So, from my limited amount of reading, I'd say the tyres are the problem this time around.
Just think, if these new tyres are causing such a problem for these multi million Euro prototype race bikes, how bad will it be on a production bike that we can buy when Bridgestone decides to push this construction to market someday?