What particular "context"? Apparently you think this features is useful "all the time" (see quote above).

I'll ask again: who is it you're agreeing with? Who else in this thread has said that remixing the front three channels is "useful for matrixed sound formats"?

2.1 and 4.1 set-ups are already covered by initial speaker configuration. The centre channel content is reduced by 3dB and split equally to the front L/R channels. Nothing further needs to be done.

You seem to be under the impression that "remixing" is happening during PLII matrix decoding, when that's simply not true. Only when a centre channel is being extracted can the extraction level be chosen by the user. This is very different from a remix function that would bleed discrete centre channel content to other speakers on a variable basis. That's a bug, which Outlaw Audio will hopefuly deal with. The solution is to fix that bug, not re-mix the source material. There is no "need to remix stems". If the problem is the speakers, then that's what should be addressed. The solution is a centre speaker that actually does the job, not some re-mix function that spreads the discrete centre content across three speakers. Because there is no re-mixing (i.e., re-directing discrete centre content) going on in PLII. This is a feature you've invented in your imagination and are now lamenting for not applied to other modes. It doesn't exist.

And for situations where you have a discrete centre channel but no centre speaker, then 100% of the centre channel content is sent to the L/R speakers. Hey, I'm just going by what you described earlier. Any centre speaker that's essentially useless for off-axis listeners is a real "problem" for any home theatre.