Every Commander, including myself, has left a station having forgotten (an important or necessary) something at least once in their career, and it likely won't be the last or only time that happens. That said, is it too much to ask that people pay some modicum of attention to what they are about? I'm sure some tractor-trailer driver has left without the trailer at some point in the history of goods transport, but is it really that difficult to have a personal pre-flight mental checklist that includes making sure you loaded up before disembarking?
You are correct to a point...
The problem I think is that the game already gives us all sorts of information that potentially it shouldn't, information that should be part of the mission planning, how far the destination system is, how far the station is from entry point, size of station, reducing accepting a mission to simply looking at the reward and clicking accept, even though
every mission description tells the player to check the galaxy map to ensure it can be completed!
I kind of accept that the galaxy and system maps aren't particularly quick or efficient to check, but still... In FE:2, it was part of pretty much every mission if you wanted to be sure you could manage it in the times given.
But the information about mission destination and origin should be part of the in-game info once you've accepted the mission, and I think (hope) FD do get around to putting this into the transactions tab at the very least.
While collecting cargo from the depot is a bit clumsy (and I have indeed flown to a target destination empty), I think that it is the players responsibility to ensure they've loaded their ship, and FD shouldn't hold our hands on that one.
People often complain the game is too simple, and I feel expecting us to think about and plan the activities that we want to do would be a positive step. Once we've decided to do something however, the information needed to achieve that should really be available in game.