The MOST important thing to check before planting b&b trees is the type of burlap used, whether it's treated or natural. If it's treated, you'd better cut it back sufficiently from the top to permit the roots to extend. It'll be a good idea to cut through the bottom areas as well. Many burlap treatments are almost like a plastic container, so there will be NO ROOT GROWTH through it if left in place. On the other hand, if it's natural, there's no issue about leaving it in place as it will biodegrade within few months depending on soil conditions surrounding it. Regardless of what you've read or heard, leaving the wire basket in place does not impede root growth, though it is true that once the size of the root penetrating the wire basket reaches the opening size in the basket, it will grow around the wire...something like 50 years later! (How long is your warranty?) And that doesn't mean it'll die at that point.
Lastly, let's face it, the sisal twine tying the basket to the trunk needs to be natural also, not plastic, for the same reasons. If plastic, you've got to cut it away so the trunk doesn't get cut into and starve the tree of nutrients, while the natural twine will biodegrade within a couple of months. Importantly, if it's natural twine, it helps stabilize the tree in the hole and minimizes, somewhat, the need for extensive staking.