Hmm. Perhaps I've had good luck with PMs. I've actually generally been impressed by some of the insights I've received from PMs about how to prioritize business interests. Most recently, there was a question of what to do in the case that data coming from the client is inconsistent with what is on the server. The proposal was to throw an error. PM said that, whatever we do, it should not interrupt or block communication, which answer simplified the remaining discussion.
Well, notice that the answer came in the form of a requirement. The PM just forgot to tell you that one up-front.
Also, your conversation doesn't reflect you asking him what to do. You made a proposal, and he clarified the requirements. He didn't tell you what to do.
I wasn't very clear on my post, but the way you did is the one that works. You go to the PM with an answer, and he says if it's acceptable (or why not). You know how to weight the technical details, he doesn't, he knows about the business details. So your proposal should be reasonable, but there isn't any expectation about any one he comes up with.
These conversations are part of the PM being considered one of the team, being part of the daily stand-up and such. If there's tension between the devs and the PM, then the incentive structure is off, somehow.
Hmm. Perhaps I've had good luck with PMs. I've actually generally been impressed by some of the insights I've received from PMs about how to prioritize business interests. Most recently, there was a question of what to do in the case that data coming from the client is inconsistent with what is on the server. The proposal was to throw an error. PM said that, whatever we do, it should not interrupt or block communication, which answer simplified the remaining discussion.