"Anonymous. Now come on. You aren't trying to say that dancing is the same now as it was when you first took to the floor."
I can assure you that the underlying principles have not changed.
"And are you saying that all those photos are mistakes. Every couple there, literaly hundreds."
Yes. It is well known that the hands tend to fly out from their ideal position.
If you take what they achieve as your goal rather than what they have been instructed to do, you will compound their imperfections with your own.
"For those who don't know we are discussing the position of the lady"
We are not discussing the position of the lady, which is about right, we are discussing the misposition of her hand and the gentlemans.
"Is your right arm as a lady as straight as those you will see in the photos."
The lady's arm is not supposed to be straight but to have a graceful bend to the elbow. A straight arm is missing a critical element of the hold. If the man lets his left arm wander to far out, the lady's arm will be straightened - but that always has and always will be a mistake, though one easy for anyone to slip into.
Let me try to explain in detail why this is so critical. The lady's shoulders need to have a presented rotation, which is to say forward and up, down and back. This strongly suggest a particular rotation of her arms. For her right arm, the elbow needs to hang slighly inside of her hand, with her palm connected to the mans. If his hand is too far out, or too far depressed, this element is broken. For her left hand, again, the proper position of the shoulder suggests a hand that is rotated to the inside of the mans arm, not the outside.
Yes, it is possible to create a good posture even with these elements of the hold missing - but it is much easier to create a good posture when these key elements of the hold are there to suggest and reinforce the posture. If you go around, you'll hear some spreading the outrageously ignorant advice that the hold is purely decorative - and theirs clearly is. But to dancers trained to use the hold as a soft and living connection, each element of a proper hold is a contributor, and non should be neglected.
There is no goal in modern dancing that is incompatible with these classic elements of hold - they get left out merely because these young and busy dancers have too many other demands on their attention, not because they are in any way obsolte. And if you did what they said rather than what the photographers catch them doing, you'd already know that.