Don't think it's a joke.
It's a mutual effort of sorting out which is which and what is what.
Merely having some skin showing in the light of day, for comfort or health reasons (moderate sunlight on skin is healthy), is not sinful.
If someone finds it tempting or offensive, it's considerate to adjust for that...to a point, for it's also considerate for the person bothered to focus elsewhere...if they cannot bear the sight well.
It's not like one side of an issue deserves all the consideration, at the expense of the other's liberty...unless that person chooses to sacrifice their liberty...then that's their prerogative.
But if/when someone is obviously weak, and someone taunts or teases them in a seductive/mocking/belittling manner - then that speaks of a serious lack of love and respect.
But if natural attraction is inherently problematic "covering up" may serve as a "band aid", but the real healing has to come with learning how to deal well with temptation, by becoming spiritually minded enough that the temptation no longer has any pull.
Being tempted isn't a sin, it only becomes a sin if we go along with the temptation.
I'm reminded of a saying, "What if they declared a war, and nobody showed up ?"
Well along that line - "What if a woman had her cleavage showing, and no one bothered to look, or thought anything of it ?"
Sometimes hiding things even adds to the allure by fostering a "curiosity for the secretive".
Each and every situation is somewhat unique, which is why being spontaneously led by The Spirit is so much better than simply following generalized rules/laws.
Is the law then against the promises of God? God forbid: for if there had been a law given which could have given life, verily righteousness should have been by the law. <-----> Galatians 3:21
This I say then, Walk in the Spirit, and ye shall not fulfill the lust of the flesh.
For the flesh lusts against the Spirit, and the Spirit against the flesh: and these are contrary the one to the other: so that ye cannot do the things that ye would.
But if ye be led of the Spirit, ye are not under the law. <-----> Galatians 5:16-18
...The fruit of the Spirit is love, joy, peace, longsuffering, gentleness, goodness, faith,
Meekness, temperance: against such there is no law.
And they that are Christ's have crucified the flesh with the affections and lusts.
If we live in the Spirit, let us also walk in the Spirit.
Let us not be desirous of vain glory, provoking one another, envying one another. <-----> Galatians 5:22-26
May The Lord Be Magnified !
wm