Jim Womack, in an LEI newsletter from November 2006, wrote:

Given the magnitude of the task and its many dimensions it’s understandable that lean tools came to the foreground: 5S, setup reduction, the five whys, target costing, simultaneous and concurrent engineering, value-stream maps, kanban, kaizen. Indeed, I think of the period from the early 1990s up to the present as the Tool Age of the lean movement.

This is a rationalisation. You cannot change a system (as Ohno did) with a tool-set.

As Womack admitted:

The attraction of tools is that they can be employed at many points within an organization, often by staff improvement teams or external consultants. Even better, they can be applied in isolation without tackling the difficult task of changing the organization and the fundamental approach to management.

This is the reason tools took off: it’s the kind of intervention that appeals to the current management mind-set and, moreover, offers no challenge to it.