Via Marketing Begins at Home an interesting article on the mismanagement of clients by PR agencies.
One thing I've noticed over the years is that at most agencies, the higher you climb the ladder, the less day to day interaction with media is expected of you. The higher ups, the Account Directors and VPs, spend their days on building new business (which makes sense) or on 'strategy,' 'drawing up crisis communications plans' and 'media training' (which seems superfluous if you aren't focused first on getting attention from the media).
On a macro level, from my own personal experience the reason most companies engage a PR firm is because they have this notion that they need to get press to get customers. Right or wrong - but I learned working at Denny's many years ago that the customer is always right.
And putting what inarguably is the client's first concern in the hands of the proverbial recent college graduates seems silly at best and a poor way to run a business at worst. Yet there they go.
Working for a small company, where the partners are very involved with clients, I would tend to agree. When more experienced PR professionals taking a hands on approach with their campaigns, not only does the client benefits, the agency does as well. Junior staff learn from working with seasoned professionals, and the client doesn't get signed up with the head of client services and then never see her or him again. Often, this is more likely in smaller agencies. I'm sure large firms work well for equally large companies, but if you're a small or medium sized business, a smaller PR agency could be just what you're looking for.