Indeed, I agree with you. The problem, which you yourself acknowledged, is that stopping these drugs (or practically any sedative) suddenly will often cause severe withdrawal symptoms. Doctors unfortunately also frequently see these drugs, much in the same way as they do with benzos and antidepressants, as some kind of cure rather than what actually are in most cases, which is a crutch to help people get back on their feet after a major breakdown, and which should be gradually tapered down and discontinued as the patient metaphorically re-learns how to walk.
The reason I suggested asking for a lower maintenance dose is that it's a tactic that's more likely to convince your doctor to concede than if you immediately discussed a discontinuation. Further down the line, once you're stabilized on your new "maintenance" dose (presuming you have no problems), you can, whenever you're comfortable, once again request a reduction in dose to a level below that, eventually reaching the point where your dose is small enough that you can reasonably suggest a complete discontinuation of the drug from your actual dose. You'd effectively be conducting your own slow taper off your medication without ever actually affirming so or saying anything else that could raise any red flags with your doctor.
). I disagree with you that a potent D2 antagonist == a potent antipsychotic, however, much as a strong SERT inhibitor doesn't necessarily imply an effective antidepressant.