If they are illegal they have broken federal law and should not vote. If they are legal residents then they should be able to vote. Pretty simple I think.Yes. But we have a constitution that speaks to that for federal elections.
States can focus on letting all the people have a say in what we laughingly call self-government. It's good for democracy, for the communities, and for America when states and localities actually let all the people participate.
Republicans tend to disagree. Not all Democrats agree, either.
What's a good argument for denying residents the vote? I can't think of one. Can you?