It's always good to pay attention to news about the voting process, but the article points out that this isn't anything nefarious:
"The voters whose registrations were deactivated have not voted in the past four years and have not responded to mail from election officials about their registration, according to a statement from the commission.
Every two years, the commission is required by law to identify voters who haven't cast a ballot in at least four years and deactivate their records unless the voters indicate that they wish to remain registered."
That seems pretty nefarious to me. It's bad enough that you have to register to vote (we shouldn't), but why would a law exist to deactivate anyone to vote that isn't dead?
Keeping accurate and current voter registration records is useful. Voter fraud is close to non-existent, probably because if you register in multiple locations, you'll definitely be identified. Knowing where to send absentee ballots is great, too.
Wisconsin has same-day voter registration, so it's at worst a mild inconvenience for anyone whose registration was purged, hasn't moved to a new place, and they still want to vote in an upcoming election.