"Sexism because of a light hearted advert talking about the obvious, ie the majority of women shave their legs."
Only obvious because shows how pervasive it still is! Why do you think there is the oft-repeated trope about hairy-legged lesbians or hairy-legged feminists? It's not light hearted when 9 or 10 or 11 year olds are wanting to start shaving because they think they'll get laughed at if they don't, or when grown women have to trim and shave and wax and god knows what else before they go on holiday because they will get comments and stares if they don't. Whereas we have all seen that most men have no problems whatsoever turning up at the pool looking like sun-burnt, flabby yetis.
And the fact that someone selling you shoes thinks that reminding you of the desperate need to shave will increase their sales?
Shaving is not benign (have you seen what razors can do to someones legs!), nor is waxing, or plucking, or depilators, or lasers, or creams. A man with sensitive skin can at least grow a beard. The sheer number of types of products for hair removal for women tells you something is up. Oh, plus the fact they charge you more for making razors in pink!
Men's beards anyway, fashions change, from designer stubble to hipsters, and back again. But the fashion that women should be hairless never seems to change now that the majority of women in the UK use such products at least once a week (although less in France, anyone else remember the hairy armpits on the continent stuff from their schooldays, and how shocked some girls were when the exchange students came over?).