Rationale (April, 2013):

There is a distinction in the core language between aggregate initialization and value initialization. For example, a class with a deleted default constructor can be list-initialized via aggregate initialization but not value-initialized.

The resolution of issue 1301 changed the status of T{}, where T is an aggregate, from being value-initialization to being aggregate initialization. This change breaks the description of DefaultConstructible in 16.4.4.2 [utility.arg.requirements] Table 19. LWG has opened an issue for this (2170) but would like CWG to consider a core approach that would categorize T{} as value initialization, even when T is an aggregate.