confused lockboxes

Right i dont really understand how these work, let me explain ....

Do you get better loot from a tier 4 lock box than a tier 2, obviously you get 4 items rather than 2 items, but surely you can buy 8 tier 2 lock boxes for the same amount of keycodes (resulting in 16 items) or 3 tier 2 lockboxes for the same amount of script (resulting in 6 items)

I hope you understand what im getting at, if the items or chances are the same and its just the number of items received then tier 3 and 4 lockboxes are pointless.

Hope someone can clear this up :(

You have a better chance to get better loot. But they don't actually tell you the chance.

if thats the case that should really be in the item description ....

I hit cap so went to buy my first T4 box.. inventory was full, oops... I never got it and lost my keys :/ All over flow items go to claim window; but apparently not the boxes.
But yeah T4 has the best chance of getting rares. And the rarest probably only from T4.