As a new player to the game I recently bought a toolbox, without quite knowing what made it different from a bigger bag. I assumed it would be a slightly larger storage piece, but just for tools. I was right about the just for tools part...
After debating in global a bit about toolboxes vs. bigger bags it does seem that they have some benefits, but they hardly seem worth the cost to a lowbie. Further I'm sure that other new players will likely purchase it assuming it must be bigger because of it's higher cost and be disappointed as well.
So I started thinking of how toolboxes could be made better. I assumed that increasing the size was not something the devs wanted (though it would be cool!) so I tried to come up with something else.
Here's my idea: What if toolboxes allowed the use of every tool inside without opening them? Instead of opening when clicked, they'd produce a large drop-down menu with the abilities of every tool inside. In essence they'd be fully customizable 16-function swiss army toolboxes.
When a tool breaks (i.e. your frypan broke) you'd replace it's use menu with a repair menu item (i.e. repair frypan. Or , potentially way more awesome, every tool inside could share durability. So instead of individual tools breaking the toolbox would break. The toolboxes durability would be the combined durability of all the items inside.
As far as tool organization goes, it would still be possible to open toolboxes to remove and add specific tools (it'd be the last option on the drop menu) it's just wouldn't open by default when clicked.