Christmas isn't too bad a time for vicars. Yes, they have more services, but the sermons are fairly standard. The work a vicar does on committees and the rounds of meetings all disappear at Christmas.
I think if FABFU thinks there is a problem, we have to accept that there is.
I think a lot has to do with attitude to clergy and disappointment when they seemingly fall short. A lot of people think that the vicar is "the church", and they don't realise that they are too. They may be anxious to get involved on something meatier than the coffee rota, but don't know how to take that initial step. It is hard to step forward in case you get knocked back.
At my church, I wanted to have more of a leadership role, but was intimidated by those who were better at just about everything than me (especially quoting chapter and verse, and being able to stop and pray with someone in the middle of Tesco). For me, it took moving away for a few years, and finding growth in a different church. When I returned, I had confidence and experience.
What I have found has worked in my church is for the various ministries to run themselves. For example, when I was a SAHM, I was actively involved in Women's Ministry. We used to work very hard at how we could be more effective in our church family and within our local community. We didn't involve the vicar or PCC at all (except to ask for occasional funds). We just had to make sure that everything we did fitted with our church's mission statement.
Other groups do likewise. We just feel that the vicar's job is to equip us with the tools to be the hands and feet of Jesus. A major part of this is in preaching the word - explaining the commandments of Jesus, the encouragement of Paul, etc.
From what FABFU has said, I think they need to go back to grass roots thinking and coming up with a new mission statement for their church (or revamping the old one) and figuring out what everyone can do, and the vicar's role in facilitating this.