I believe the same thing as you, but IKEA invested a lot in their own 3D tool and they probably prefer to keep a full control on their 3D models.
At the opposite, you find so many IKEA 3D models on Trimble Warehouse and elsewhere, that I would be astonished they are not aware of it. If ever it goes too far, maybe they will require their removal for copyrights infringements. Nevertheless, they should state their choice more clearly.

Please, keep us informed of their answer.