I have referred to “changes that would just take 5 minutes to make” before. There must indeed be cases where the fix really is that simple: I remember one case where the problem was a misplaced decimal point. Most of the time, however, the players saying that have no idea what they are talking about. And the developers want to hit them. If the fix really were that simple, it probably would have been done by now, unless the suggestion is also some stupid balance- or game-breaking idea. No, fixing the AI is not just a matter of telling it not to jump off the cliff. That is a complex behavior to teach it, and teaching cliff-avoidance might break half a dozen other things.
Do feel free to continue browbeating developers for having hard-to-modify spaghetti code. Documentation may seem optional when you need to release in six weeks, but six months after release you may not still have the guy who remembers what half the variables mean. The more flexibility you can build in at the start, the better your reaction time will be later.