Too many PMO staff, in my experience, seem to think that the main purpose of a programme/project is to produce management artefacts, e.g. Risk Logs, reports etc.
They lose sight of the fact that the PMO is there to help the project achieve success via efficient and effective governance processes.
I worked on one assignment recently where the PMO person allocated to the programme had no concept of what the programme was delivering - despite my best efforts to explain it and have her read the Business Case, Vision etc. - and was simply hell-bent on having the Risk Register updated on a fortnightly basis. It wouldn't have been so bad if she insisted that the risks were actually managed, but it was only the documentation she was interested in!
Once she was removed from the programme we delivered on time and to budget, and our governance satisfied successive OGC Gateway Reviews with no-one from the PMO assigned to the programme.
I've managed other programmes where PMO staff understand that they are there to add value and to help achieve the end-goal, and in those cases they have been a tremendous aid to the programme. It's all about people understanding why good governance matters.