I have a very ambivalent relationship with agents. You may have noticed that.
When I started in the business, agents weren't a necessity. But I eventually got one--Carol Mann. I might as well start naming names. Nothing was going on in my career particularly, I was doing books for Atheneum. And I don't even know why we stopped working together although I imagine it was the desire to move into television.
I've had far too many agents. I wanted it to be like the old days when you got an agent and stayed with them for 30 years. Of course I think it was Bob Shanks who said agents are best changed every two years, and I suppose that's how it went for me.
Over the years, many agents (not all, not my current agent) have taken on an elitist attitude and given the circumstances it's understandable. Publishers have made them an integral part of the equation. Publishers need agents to keep substandard writers away from them otherwise they would be inundated with stupid manuscripts to read. Agents are also inundated by stupid manuscripts as well as good ones (which they fail to detect on a regular basis), so they've become pressured and rude. They are psychologically unsuited for the exigencies of this reality. Agents who once were helping writers, now see themselves as helping publishers. They're facilitating the publishing of units (otherwise known as books).
I was somewhere yesterday, some blog, where an agent was frankly stupid enough to complain about writers and that person was lambasted enthusiastically. I joined in as well, something I don't often do. It has to take a debilitating sense of elitism and entitlement to insult writers at this point in history when we're running from tradpub to the digital format with great enthusiasm and relief.
I think the question becomes what can a publisher do for me that I can't do for myself. I actually am hard-pressed to come up with reasons beyond some money up front. Luckily for agents and publishers, all writers haven't gotten to this point yet.