Not everyone wants an inclusive definition, some people want discriminatory definitions. And I don't mean discriminatory in a negative sense. If "four" means 4, it would be more inclusive if it also meant 5 and 6, but it loses some utility in its inclusivity.
My problem isn't with your definition, it's with your implied assertion that we should "we want a simple inclusive definition," which is clearly not the case, as the differing priorities in definition are literally central to the debate.
If we want a simple inclusive definition, you can't beat that.