Agents are in it for the commission, you guys for the fee. Some work has potential but needs a professional touch to be sold to a publisher. clearly, agents and freelancers can do very well together, assuming they don't mesh their interests to the detriment or deception of the author.
I think if agents know of good editors, then the agents can steer potential clients to those editors and the agent, writer, and editor can become a team. If all goes well, this team can work together actively toward the goal of the writer getting published. Of course, there will always be people out there to take advantage of writers (and probably agents, iof such a thing is possible,) but I also think there are plenty of people out there who want to work honestly and honorably together. I would certainly love to be a part of such a team, whether on the editing end or the writing end. This could even become a new way to pitch manuscripts to publishing companies, which are farming out services like editing to freelancers or others anyway.
There was one agent who was offering editors a percentage of authors' advances and a percentage of the royalties if the editor referred the author to that agent. The problem was that often the agent failed to place the books with publishers, leaving the editor high and dry having made no money. So clearly that model does not work.
What I would like to see is agents and editors matching themselves by the types of books both are interested in, or for an agent to have a list of trustworthy editors suitable in specific genres, or, in the alternative, a list of trustworthy editors who have proven that they can be highly flexible and eclectic. I agree with you that agents and freelancers can do well together, and most importantly can help authors create more saleable books. The challenge is to come up with the right livelihood model that would avoid taking advantage of eager emerging authors.
Just today I received a phone call from an author whose agent had recommended me as an editor. The agent already has an interested publisher for the book, but had noted that the author still needs some stylistic polishing and a good copy-edit before the deal can be done with the publisher. So the author and I worked out a fair price, based on the number of pages to be edited. For this author, investing in getting this promising manuscript further polished is a good bet, since there is already an interested publisher. For an author who does not yet have an interested publisher through his/her agent, but who needs editing services in order for the book even to be pitched, it's a bit more problematic in the sense that guarantees of publication can never be made until there is actually a contract on the table.
I think agent-editor teams would be particularly useful to help emerging authors--authors with talent and a great story or topic--that have the potential to break into the trade publishing market. But it will take both ethics and creativity to create the right livelihood model to make it work for the good of all three--author, agent, and editor.