Why can't Riot give some context on the Garen changes?

Seriously; so many of us are asking why they chose to hit that out of everything in his kit.

He's already a low mobility champ and it just doesn't make much sense unless they're trying to appeal to players that don't know how to kite or can't CC properly. If the problem emerges when Garen picks up Deadman's Plate, why not nerf Deadman's Plate? Garen's not the only champion that item is ridiculous on.