KAT was a part of a previous era
The key elements of the Minnesota Timberwolves roster have come together fairly recently. It all began with Naz Reid being signed in 2019 as an undrafted player, Anthony Edwards and Jaden McDaniels being drafted in 2020, Rudy Gobert being traded for in 2022, and Mike Conley being acquired in 2023. Karl-Anthony Towns, a part of the previous build for the team, was drafted in 2015. Even though he was a productive and important player for the team, the argument could be made that he didn't fit in with how the team was moving into the future.
He was not a pick by Tim Connelly, who was hired as the team's new President of Basketball Operations in 2022, and his contract was absorbed by this most recent administration. That doesn't automatically mean he should be traded but it's also understandable why it needed to happen.
With the rise of Edwards, I'm sure Connelly wants to build his own star support system around him. And the honest truth is that it probably would've been impossible to do with KAT still on the roster.