Consider:

  const int arr[2](1,2);

This is accepted by all major implementations, yet 9.4.1 [dcl.init.general] paragraph 13 prohibits it:

If the entity being initialized does not have class type, the expression-list in a parenthesized initializer shall be a single expression.

Presumably, this was an oversight when adding parenthesized aggregate initialization.

Possible resolution:

Change in 9.4.1 [dcl.init.general] paragraph 13 as follows:

If the entity being initialized does not have class or array type, the expression-list in a parenthesized initializer shall be a single expression.