In ANY "uncommon" lifestyle, there will be those who are abusing it for their own "gain" (usually destruction).
I DEFINITELY know people who use polyamory as an excuse to continue self-destructive behaviors. In fact, I was told I wasn't poly because I'm not "addicted to falling in love".
But-just because people use it that way, doesn't mean it has to be that way.
The thing with emotional connection issues, is that they are almost always driven by underlying fears. The solution (imo) is deep, personal honesty and personal inventory.
Much like in AA, it's highly advised not to start any new relationships for the first year or two; it would make sense that if you are trying to resolve major emotional issues such as you describe, that it might be best to not begin new relationships while you work through that.
But that doesn't mean you can't make progress towards having healthy relationships.
I don't think mono or poly has anything to do with it. But-if you find yourself not making deeper connections, maybe you need to work on really opening up to yourself and then opening up to others more deeply before engaging in romantic relationships?
"Love As Thou Wilt"