Rationale (October, 2012):

The rules are acceptable as written; declaration and expression contexts are different.

Dealing with aggregate-initialized temporaries has been a bit of a headache because unlike aggregate initialization of variables, each element initialization is not a full-expression, so various things behave differently because they are in the context of initializing a temporary.

This can either be inconsistent with aggregate initialization of a variable (in which each element is a full-expression) or inconsistent with list-initialization via constructor (in which each element is a subexpression).