The whole hierarchy of needs (thank you, Mr. Maslow) are things that are important to humans. Working to address each of those needs, in turn, is the mark of a healthy human--as long as those needs are addressed in a healthy fashion.
Problems arise when a general need--that of companionship--gets corrupted. We have a need for companionship and we fulfill that need by finding companions. When we treat that general need, instead, as a need for a specific person--instead of recognizing that many other persons can provide what we need--then the fulfillment of the need is twisted and dysfunctional.
So, there's nothing wrong with needing other people and relationships with them, whether romantic or platonic or varying in wild and wondrous ways. There is something wrong with perverting that general need into a need for a specific person. Even within a relationship, while one needs a partner or partners to fulfill the need for companionship, it's only healthy if one can walk away if the relationship(s) become(s) toxic.
While one should want a specific partner, that desire should rest on a foundation of only wanting that partner if the relationship is healthy. If it turns otherwise, then the desire for that person should flag and one should be able to walk on. If one *needs* that person in spite of the toxicity of the relationship, then there's a major problem. That form of need is unhealthy.
When speaking of various forms of non-monogamy...it ain't poly if you're just fucking around.
While polyamory, open relationships, and swinging are all distinctly different approaches to non-monogamy, they are not mutually exlusive. Folks can, and some do, engage in more than one of them at a time--and it's all good.