Yes, we do.
Football has changed a fair bit in the last 20 years. The role of a manager was far more akin to a current head coach in the days where transfer windows didn't exist, money wasn't huge, and players didn't have as much power as they do now.
Add in the ever-increasing compexity of media relations and the likes and it's easy to see how much the role of a "traditional" manager has grown. It's far too much to expect someone to be in charge of all of that.
When you consider our more successful periods in recent years, we rarely came out of them with a longer-term stability. We didn't have a number of good youth prospects playing in the first team or such like. The closest we came to it was Walter's second spell, and we obviously got shafted there.
We need to let the coach concentrate on results and let a DoF take on the long term planning, scouting team, target identification and overall club philosophy. If it's all down to one man, we'll see loads sacrificed in the name of getting results, purely through self-preservation.