Criminals lose numerous rights. Gun possession, voting, freedom of movement, freedom to live in certain areas, freedom of association, all sorts of things. Similarly, they can apply to have these rights restored. No difference here. To continue with your analogy to criminals, which is not especially apt, sex offenders remain registered often for the rest of their lives and are subject to some degree of monitoring. As are parolees. Again, no differences. It's remedial, to ensure they don't re-offend or to lessen th chances of recidivism. Same here with jurisdictions that have proven untrustworthy. Many people with DWIs are indeed forced to use a built I'm breathalyzer for a substantial period of time after.
You keep overlooking that any jurisdiction that can meet the burden can have the automatic review lifted. If they don't need to be babysat, they can prove it.
Mechanisms exist through which claims can be brought, such as the NAACP, etc., but why rely on that exclusively?
What's the benefit that you see in relying entirely on costly and time-intensive litigation for the protection of voting rights as opposed to simple DOJ review of states who we unable to prove they no longer discriminate in the process of redistricting?