These are exactly the same as the more expensive boxes, the stiff bottom comes with them, just separately, you have to insert the bottom yourself.  These are neither thinner, nor more fragile, they simply require the easy step of inserting the box bottoms into the boxes.  I'm sure the people who complained were surprised to find that they had six extra parts left over after assembly!!  Reading the instructions is always preferable prior to assembling even the simplest of products!  These are well worth the price, true to color, and just as sturdy as their more expensive, individual counterparts.  An excellent buy.