It would be nice to have a water resistant nook to store registration and insurance card without exposure to elements. The only other concern I'd have is rear wheel articulation UNDER the seat storage box.
For me, this has been a concern for sometime as I had years ago spent many riding hours on a vespa scooter overseas. Honestly its the ease of abundant storage options that make scooters so attractive. Having such horribly bad road and highway conditions here in my community, the TW's over-sized tires actually assist in absorbing such calamitous pot-holes and the like. I have read within these forums where other owners have installed Panners in addition to various box's atop the numerous racks available. This... at least for me, is the very reason I have selected the TW as my future runabout.
Any amount of additional storage would be a welcome addition.