Then your senior rung is probably unpromotable and will become useless; you're just paying a premium on entry level skills. Architects don't code; they care about broader, higher level things. So it's natural that seniors move away from coding to those more abstract tasks over time. Your juniors should be generating most of the code. If I had a lead/senior who wrote most of a system's code, I would be alarmed. He's not distributing the work (and knowledge of the codebase) and doesn't seem to understand his role.

Where my opinion differs from yours manifests itself in industry in the practice of separating "technical leadership" from "people leadership." Your architects (and leads) should be people managers. They should have authority in how their subordinates' time is spent. They should be able to resolve disagreements, both technical and interpersonal, among engineers. A "technical leader" designing large systems/platforms to be built by a team that's led by a "people manager" is pointless. I mean, who wants to design something without the authority to execute that design? That's a toothless fluff position.