A near impossible literacy test Louisiana used to suppress the black vote

Beyond anything else, intentionally designing a political system around disenfranchising a class of people seems like a bad idea from a human rights standpoint. You're creating a system in which the wealthier citizens can systematically take the rights away from the poor. I think you know how that can go wrong considering you're asking this question specifically on this post out of all posts.

All extant and historical systems explicitly disenfranchise some people, children, criminals, foreigners, etc.

And we should work to remove such disenfranchisements from the system rather than simply accept them as a law of nature.

Why? Most people find it beneficial to disenfranchise criminals, don't want murderers walking free and hurting you. Why should people support policies that hurt them?

Citizens convicted of crimes are citizens just like you (I assume) and I. I don't think most people find it beneficial to disenfranchise them.

One obvious use case for not disenfranchising citizens convicted of crimes, is a politician who criminalizes opposition, thus making it impossible to vote them out.

As for policies which hurt people: policies favoring old folks often hurt the majority of people, but there isn't a big push to disenfranchise old people.

Unless you're arguing for the summary execution of all felons, we already allow murderers to walk free after serving their time. Hell, when those murderers are soldiers we give them medals and parades.

Sorry, technically those soldiers are killers and not murderers since when they take innocent lives it's endorsed by the state.

But if you think the presence of felons within society presents a social or public safety issue, consider that the real problem is that the justice system in the US is punitive and exploitative rather than rehabilitative, and what cultural and systemic issues might lead people to crime and violence in the first place, and to recidivism.