As for me, I think that there are a lot of legitimate complaints about how some agents do business. For example, I agree with the many authors who do not like the agents who have a "I reply only if I'm interested" policy. My other gripe is agents who demand "exclusive" queries and then ever respond. Obviously, authors can't follow those agents "rules" or they'd loose all chance of selling their manuscript.
On the other hand, I also think that these types of gripes will do little good. Unlike some authors, I don't fear that a post like this will get me blackballed by some agents. However, authors have to face the fact that agents occupy the ultimate buyer's market. And the more successful the agent, the better market they occupy. So, it is only human nature for agents to arrange the submission process in a manner that works best for them. Unless a massive change in the publishing process occurs, authors are simply going to have to live with that reality.