So I tend to wrack my brain daily over the question of whether this game is just hard to penetrate for some people, or if those people are infact just retards...
It's conceivable that newer people don't understand this is how the game has evolved...on the other hand, it's also entirely possible those people just don't care about the other crew and do whatever the hell they want...it's also arguable if this meta should be kept, but as things stand the reasonable for it is fairly sound.
Anyway, I just had an idea, a bit of social engineering that might steer people in the right direction.
In the lobby, where it says 'Click to Captain/Crew'...just put the Engineer Wrench symbol inside 2 of those boxes, somewhere along with the text, put a Gunner Bullet in the third crew slot, and put a Steering Wheel symbol in the Captain slot box.
Not much, but it might be something to engage peoples brains and get them thinking that maybe they should organize themselves like that. Mind you if it works better than expected I can see people getting bitched at for not going gunner in the gunner slot etc. It also doesn't account for the people who don't even understand what class they are, or how to switch, but maybe a greater emphasis on symbol association might work.
Addendum - Or, having double checked how the lobby looks, instead of just having the empty slot say "AI Crewman" have it say "AI Engineer/Gunner" instead, as an alternative to the symbols thing...of course then that would need to correlate to actually getting an AI crewman of that type once ingame, and if the code isn't already in place, well, extra work :s