Which is more fun to play according to you?
I don't do virtual second jobs. Unless its a job that involves killing lots of people with guns, lasers or swords.
Someone loves all those dumb omgpop games, so don't knock it! Lots of people like being healers in MMORPGs and nothing is a dumber, simpler mini-game than watching bars and hitting "HEAL" over and over for hours. (I'm not saying *I* like these things, just that lots of people apparently do because they keep playing them.)
I would envision the engineering game to be something more like managing a host of automated repair bots. You need to adjust them and tell them what, in particular, to repair. Otherwise they will just repair in some generic, probably not optimal order.
I also see "ship crew" as a number of positions that people can shift between freely.
That is 1 person can crew an entire ship by switching freely from station to station. "Okay shoot some torpedoes now adjust the engineering to work on the shields now load some marines into a boarding shuttle now back to shoot some more torpedoes now turn the ship around..." But ideally you'd probably want at least 2-3 people per ship to prioritize things. And for boarding actions you would need some pool of ready players you could draw from as needed. Maybe they could log in and man a random gun or engineering station until needed for boarding combat. That's not any worse than standing in a shieldwall or hiding behind a tree waiting for that horse to ride by.
Incidentally, "tank driving" was always one of my favorite things to do in Planetside and WW2O. You have to pick a good tactical position and sometimes haul ass. I thought it was fun even if I didn't get a gun to shoot. A dedicated "pilot" position would probably be plenty of fun.
WW2O is a good example of the type of multi-crewing I'm talking about too. 1 ship had something like 9 positions but you really didn't need someone manning the left-side .50 caliber MG full time. 3 people for the whole ship makes it like 90% functional.