Needing can partake in emotions; emotions being volatile as they are cannot guarantee basic necessity for they can arise from unnatural states of mental affection and distress; yet, a need surges in the form impulse. Is it justifiable as something obligatory? not necessarily. Do we need a drink when under stress? Maybe yes. I don't think the important aspect here is the end but the need-generating impulse.

Is your question regarding the difference of needing something out of natural necessity in contrast to those needs that no matter if surfeited still generate a need? or also about the needs arisen from a desire that does not respect basic necessity?

Done it for you.

It's a fair question; you should tag it under etymology aswell to seek meaning in the very root of the word. Old English neodian "be necessary, be required (for some purpose); require, have need of," from the same root as need (n.). Meaning "to be under obligation (to do something)" is from late 14c. Related: Needed; needing. The adjectival phrase need-to-know is attested from 1952. Dismissive phrase who needs it?, popular from c. 1960, is a translated Yiddishism. If you're looking for a deeper meaning for need in contrast to desire, that would be more of a philosophical question rather.

Agreeing to an edit suggestion but user deleted.

There, edited the question... and yes.

Fixed it.. I pasted the wrong definition and didn't check. Thanks!