It's MORE important for a prisoner to have a say in the laws keeping them imprisoned for those laws to be just.

Let's say a new fascist regime says everyone with green eyes goes to jail. That's a lot of people who think that law is unjust who are now just voiceless slaves, it's self-perpetuating. Now use this for civil rights, LGBT, on and on. Revoking a citizen's vote in addition to their freedom demonstrates how a perceived right gets devalued to an easily revokable privilege.

Its essential for any society that claims to value democracy, like the democratic republic we play pretend we are, to maximize enfranchisement, especially to those that fall subject to punishment of our laws.

But let's be honest. We don't even get a vote on the economy, just 2 bribed parties that differ on the social issue symptom management of said economy. We were never what we claimed and believed ourselves to be at any point. We're a gold plated, antisocial garbage oligarchy.

You didn't see any benefit in locking up people like Donald Trump and Jeffrey Dahmer?

I'll be the first the point out that many—perhaps most—felons aren't dangerous, but some of them clearly are.