I fully understand the acoustics behind cupping your hand behind your ear, and have been known to do it myself on rare occasions, maybe in a very noisy session or sitting next to some loud instrument, just to be able to hear my own voice. But not keen on seeing it being done routinely throughout each and every song.
And, yes, I find "Big Edna's" hand waving quite extraordinary, and Karen Matheson does the flappy thing (what the heck is that about?) And no, the people I'm talking about are not Indians. They are mainly these young up and coming British artists doing a continuous and persistent up and down movement of one hand throughout the whole song: it's an unnecessary and distracting mannerism: I repeat, who is teaching them to do this? Maybe you've not witnessed it yet, but it does appear to be a growing trend!