Necessary in itself denotes what cannot fail to exist; a possible being can exist or fail to exist in itself and depends on another for its existence. The originated world belongs to the second category.
If an eternal Creator is said to produce a world necessarily, one must ask whether this necessity is intrinsic to the world or follows from a particular theory of causal necessity. A possible thing does not become intrinsically necessary simply because it is created.
On the Māturīdī account of voluntary action, not everything within eternal power must exist eternally. Otherwise the temporal origination of creation would be denied.