Your omni-tool - the thing on your arm - uses minerals, etc to make ammo for your weapons apparently, so that's what is really in the boxes.
It's mentioned somewhere in-game, but I can't remember where exactly.
Hmmm. Okay. A bit hokey if you ask me.
I'm getting a bit more in to it. There is a hell of a lot of poorly designed busy work though. I thought they would have learned from Dragon Age Inquisition. You have to go back to your ship to do some really basic things. Why is there only one terminal that can get your email? Why can't you equip weapons you pick up? Do I really have to go all the way back to the big station thing just to hear one line of dialogue etc.
If somebody had invented the smartphone, the ME universe would be infinitely more efficient!