You said it exactly right. It took a lot of guts to embrace that genre especially in those times, and take the risk of being labelled as a club singer but she did it anyway and she owned it! 
I'm posting this Tamil song because otherwise it will go unnoticed which would be a shame. As it is, Asha's contribution is overlooked in this one since its helmed by so many heavyweights: Mani Ratnam, AR Rahman, Vairamuthu, Santosh Sivan, Saroj Khan, Mohanlal and Aishwarya Rai. But the way Asha's voice glides and caresses? Wow! Jazz is not an easy genre to sing especially for someone used to structured singing but Asha knocks it out of the park. One of my favorites from Iruvar that I think is one of ARR's best soundtracks.
https://youtu.be/TAPHomV3J1M?feature=shared
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