could it be that I play with motives static and maxed (because I'm weird like that :p) and that's bugging it?
I dunno... I think this could very well be it. When you play with the needs static and maxed, Sims lose whatever little free will they have. Without any needs, they lose any motivation to do anything. Even though there are obviously actions in the game that are not directly related to the six basic needs, when those maxed and never change, my sims just stand around aimlessly and I need to direct them for every action. I assume the same is true for you?
Now, I know this should only apply to your active household, but in my mind there's a slight possibility (however remote) that you've got a whole town just standing around staring into space. It
shouldn't work like this, but it could just be a glitch. The first thing I'd try is making the needs dynamic again and seeing if that fixes anything. If it doesn't, then yeah, you might need a new game.
As you'll see from the previous discussion, quitting the career and rejoining might also help... you can always use testingcheats to pick up exactly where you left off in terms of career level.