Mermaids and their bodies (if they existed in the first place) -- and how they appear in images historical and modern. Modesty?

This question pertains to mermaids (if they were to exist) and how they are depicted in art and popular culture nowadays.

If you go to an images collection – Google Images, for example – a huge majority of mermaid pictures show fish scales and the tail beginning roughly at the waist and continuing southward. Historical mermaid pictures generally show a nude upper torso, while more recent mermaid pictures – and particularly anything from the last 30 years, show bras, some sort of pasties, or very cleverly draw additional fish scales covering the chest.

If mermaids were truly aquatic, would they need artificial coverings for their chests? Or is it safe to say that the specific functional needs relating to a mermaid’s swimming abilities are being mis-represented by artist and filmmakers in order to make their works more saleable, by not offending people who dislike the human body?