There are built-in events that don’t have parameters, so your suggestion doesn’t work there. So implementing that would mean you have pretty inconsistent behaviour based on what APIs you use, which doesn’t seem good. As you point out, you’d have to add a dummy parameter to BindableEvent as well if there are no arguments to begin with. Really hacky!
Throwing an error when timing out would (seem to) be the only option to both provide backwards compatibility for all cases and also implement your feature in a clean way.