I currently feel that jealousy in polyamory is often just a hangover from monogamy, to be "owned" by oneself, but sometimes jealousy signals real problems in a relationship dynamic that needs addressing.
Jealousy is a feeling that's naturally occurring in nature and as such, needs to be respected much more than is generally the case in all of that "polynormative literature" you reference. Where many people run into trouble is in efforts to
overcome jealousy instead of recognizing that it's an alarm signal and sounding off for very good reason. Whether that reason is the desire to own, (granted, a desire of debatable benefit) or insecurity, the alarm is nevertheless sounding off. Where I see a lot of people run into trouble is when they respond to that alarm with, "I shouldn't even have this alarm system set up in me, so I think I'll try to dismantle it, but geez, that blaring air raid signal is sooo loud!!!" Our emotions aren't experiences to be overcome and controlled, they are our guidance system and always steering us in the "right" direction. The problem is, many people do not respect what their feelings and intuition are telling them. Jealousy exists for a reason and no amount of effort to overcome jealousy is going to change someone who's not ready for multiple love relationships into someone who is. Jealousy indeed signals problems in a relationship and like fear and worry, is an emotion that comes from pain. What do we do when the body feels pain? STOP whatever it is we're doing! Stop, back off, slow down, respect the pain. It's there to protect the body from further injury. Same with our negative emotions.
Jealousy, in and of itself, is not a problem. Many people take jealousy as a sign of affection, devotion, love - and the absence of it as a sign of disinterest. Doesn't mean these people need to overcome anything or that they're neanderthals, it just means that they do not want to share their love mates. They respect jealousy and respond immediately with no internal discord - therefor, no big relationship problem. There's a reason that Mother Nature wants the majority of mates to protect what's "theirs" and there are often good reasons for jealous feelings. The poly community obviously questions this and says that not everyone experiences jealousy and in fact, celebrates shared loves ones, and of course this a beautiful concept that some of our world seems to be opening up to. But the fact remains that jealousy is not a failure, nor is it a shameful emotion to be overridden. It's a strong, clear, internal alarm that if not respected, will find other even more powerful ways to deliver its message.