So I had this all written out. It was like 2k words. But it felt like a rant when it wasn't meant to be. And then I got to the end and realized that it all boils to one thing: Respect.
Both agents and writers have a responsibility to respect each other. To communicate openly and honestly. That's it.
If you (a writer) doesn't like an agent's policies, don't query that agent. And if you (agent) want writers to do things a certain way, then post those policies in clear, plain language and make them easy to find.
But it's all about respect. Writers should respect an agent's time and policies, and an agent should return that respect.