It appears this bot could be about 100 times simpler if they just had storage racks with smaller cubbies at the modest expense of usable storage volume. 1 item per cubbie.
Generally speaking space is the most valuable commodity in a warehouse (up to a certain height).
A robot that costs 5x as much but yields 30% more usable space is a better value proposition.
Also you wouldn't be able to accommodate anything besides items that fit in that specific pick bin (what a cubbie is called in the industry), meaning you would always need a near perfect match of # of bins of a specific size to the # of products matching them. It would be a continual battle to change racking as products move in and out of the warehouse.
A more complicated robot is a better robot, in this case.