Personally, I think there are a couple of issues.
I am not sure about the “too many managers” mantra. There are far fewer managers in virgin than in comparable airlines but I am not convinced they are in the right places. At the end of the day someone has to do all the stuff to support the troops actually making th aeroplanes move. Not enough people in the appropriate roles means things that need to change don’t, things that need responses back to crews don’t get responded to, and the people at the coal face feel like they have no support. The other thing to remember is the “managers” are people too, not some mystical being that is immune to the same pressures, issues and stressors as the rest of the workforce is. Training managers or more appropriately people who hold managerial roles would be a great start.
And more importantly the business needs leaders not managers. I don’t mean titles, I mean people who can actually lead, inspire and motivate their people. Those sorts of people in those roles are a bit thin on the ground.