:

Because tool cabinets(and file cabinets for that matter) are
considered heirlooms - something to be passed down from
one generation to the next.

Also, durability. Some folks are just naturally rough on tool
boxes and file cabinets. They use the top of a tool cabinet
as a makeshift bench for quick minor repairs, and overstuff
file cabinets to the point they will no longer close fully or the
sides actually bow out.