We planted the magnolia and discovered it had wire basket around it. An arborist said this is good..... is that right?
There is nothing good about a tree placed in its final planting site having wire around it. A fully informed arborist would not state that it was good that there was a wire cage between the roots and the soil outside the rootball.
It was confirmed by two reputable nurseries that the tree should be planted in the ground with the basket
The Myth of Mighty Roots: "Wire baskets will not interfere with root growth of transplanted trees" (PDF), for your reference.