If we assume no free will, the notion of "excuse" doesn't really apply. In a world without free will nobody opts for excuses, they just do what they were predet

If we assume no free will, the notion of "excuse" doesn't really apply. In a world without free will nobody opts for excuses, they just do what they were predetermined to do mechanically. People have no agency, in any meaningful way. So, if "wanting" corresponds to some mental state, people will be predetermined to have a single specific state about it (" wanting" to punish or not punish criminals) at any given time. They will also be predetermined to punish or not punish criminals - they can only do what they end up doing. Thus, if we assume no free will, there's also no meaningful sense to say that "people hide some true intention". Nobody has any intention, same like a rock doesn't develop any "intention" to fall to the ground when it does so, it just falls. As for the question: since very few believe in any lack of free will, society will continue to punish criminals anyway. It's not like jail time and legal punishments are in even the remotest real danger to stop because of philosophical discussions about free will. So that can't be what's causing the tiny minority of people interested in such matters to advocate for combatibilism (and thus, no case of "true intention", as if they're sadists who don't want society to skip punishing people who crime without free will). Rather, a more obvious intention (again, assuming free will exists, and people do have intentions, even if they themselves believe there's no free will) is to make a universe that's deterministic (and thus traditionally understood to lack free will) compatible with the experience and intuitiveness of free will (hence, compatibilism).