Just to be clear: you're welcome to post polls on the stories if you want to. As you said, anyone can do so; it doesn't hurt anything, and if people find it interesting and want to cast their votes, that's great.
But I can't promise you that it will have much -- if any -- influence on my story selection. I'm interested in people's expressed opinions, but I'm not running Escape Pod as a popularity contest. I expect that most listeners enjoy the stories more often than not, or they wouldn't keep listening, but I don't consider it essential to get a thumbs-up from every listener every week. It's nice when everyone loves a story, but it's not my only goal.