Unity, not uniformity, must be our aim. - MPF
For me, if I had to answer to your question with only one word, it would be "leadership" BUT it is not possible to understand the follettian leadership without understanding the whole conceptual edifice: integration - circular response - law of the situation, etc.
Without any doubt, Follett has proposed a vision of leadership that was in opposition with the ones proposed by Taylor and Fayol. And still today, her vision has not been completely rediscovered. I think that managers are still fayolian leaders (and you Emmanuel, are you a folletian manager?).
So if your question, Emmanuel, was "did Follett contribute to change the world of management?". I would answer: unfortunately no.
I'm speaking from the heart with a first thought. Follett truly valued the importance of the individual's point of view as a critical reality of the whole. For example, if women couldn't vote, it was the whole that lost out on their contribution as well as the women on being part of the whole. Free speech was not just about the civil rights of the individual to voice their opinion, but of the whole's need to have that opinion. Translate this strong belief of hers into the world of business and one must integrate all employees, who at every level can make contributions, and who constitute the whole, into the dialogue about how to make the particular business a vital and successful part of the society as a whole. This turns business from strictly a profit-making enterprise into an heroic adventure. I do think she thought of businessmen, certainly the ones she liked to hang with, as lively, adventuresome, willing to take risks, striving to be ethical, and able to try things rather than talk about them for too long. She respected them and urged them to find "the soul of their work."