Personally I would never encourage a player who types out in all bold that they choose not to use mods to do so. I believe the OP has engaged in that conversation with us before, under a prior screen name.
The game is what it is, mods made by professional programmers and that have their own support systems in place have the capacity to make it more enjoyable or at least a bit of a different experience. But what we don't need is players "yelling" at us before we've even suggested anything. :/
(I know the OP wasn't really "yelling," but the intended emphasis can just look that way).
That being said, Free Will going out the window entirely is indeed either an early sign of an overly stressed game engine or possibly the result of a glitch such as the well-known one that strikes some (not all) households having large dogs and bathtubs on the lot. Even with Free Will working just as it should though, sims are not always going to do what we want them to do as they can be stubborn and have other ideas as to what constitutes running a household and their own lives than we do. :)