First of all:

+1 to Sven's very well-expressed support of the proposal, and

+1 to Nick's very well-explained reasons for rejecting it.

As one of the main implementers of PEP 448, I have always liked this, but I suggested that we leave this out when there was opposition since there's no rush for it.

Regarding Steven's example, like Sven, I also see it this way:

[*t for t in [(1, 'a'), (2, 'b'), (3, 'c')]]

should mean:

[*(1, 'a'), *(2, 'b'), *(3, 'c')]]

Which coincides with what the OP is asking for.

At the end of this discussion it might be good to get a tally of how many people think the proposal is reasonable and logical. I imagine people will be asking this same question next year and the year after, and so it will be good to see if as familiarity with PEP 448 expands, more people will find this intuitive and logical.

From a CPython implementation standpoint, we specifically blocked this code path, and it is only a matter of unblocking it if we want to support this.

Best,

Neil