The problem is that on its own, this is just a flippant remark and without thinking any more deeply about it, the people who have posted this will think it's just 'clever' marketing to aim products at certain groups.
I tried explaining to my BF about the whole 'pink stinks' and let toys be toys thing the other day (he has 2 DDs) and he didn't get why it was such a problem. With DSs and DDs myself, I see the differences in the toys that are aimed at them, in their reactions to certain ideas, and I see how society is training them to behave in certain ways which a couple of years previously they would never have considered.
Don't take it to heart that they didn't immediately see the error of their ways and just hope that your comment made one person think "oh yeah, actually my DD might like the blue one".
Oh I'm not taking it to heart as such, it's just the immediate response of "lighten up" has obviously been made without any deeper thought as to why I would have made such a comment in the first place. I'm torn between answering, "Yes, you're right! It's almost as funny as having your toy aisles colour coded pink and blue at Christmas time," or just ignoring it.