Wanting still isn't wrong. Wanting something you don't need isn't wrong. Want isn't true or false. You can't be wrong for wanting something, getting what you want can be wrong but the act of wanting it isn't.
I am not saying wanting something is wrong.
I said, people can be wrong in what they want.
That means, you can not be mistaken in the fact there is the feeling of want, but this feeling is directed at the gratification of obtainnig the item/thing/feeling etc of your desire. The item (etc) itself or wether it is capable of gratification for you is however not necessarily recognised properly by people.
Example: my kid points at a given doll in the shop and says: I want that doll.
Obviously she is not wrong in her secure knowledge, that she wants it.
However wether obtaining the doll would make her pleased or upset because she'd realise it is not what she wanted is a different matter.
One must ask then: what is the kid looking for in that doll that makes her want it. It is the playing with the doll (any doll would do), is it the brand (any other item from that brand is good), is it the dresssing up the doll (any other item, that you can dress up, or design dresses is good).
See what I mean?
We all want a good game. However we might be wrong in listing what exactly makes the game good for us. In a poll that is what can be asked: what aspects do you want? And maybe if we get each little detail we want, it might turn out the end is terrible. (Like a friend's house, he put in the house everything he wanted and loved, but he didn't consider how the pieces fit with each other, so the result, he hated.)
As for the saying, I do admit (and I think it is quite visible from my style, regretfully), that English is not my native language, alas linguistics elude me at times. In my language this saying can be used in various situatoins and for describing various scenarios. One of them is exactly what I aim at: at times you realise, what you wanted is not what you wanted at all.
I am pretty sure people wanted to buy DA:I. Some of us still claim, we wanted to buy it, and this is the game we wanted. And reading the forums points out, not all people wanted -this- game. They wanted something else, but it doesn't change that originally they were secure in their knowledge, that they want DA:I, and they got DA:I.
And the relevance: a poll can not measure the real needs, only percieved hopes. Game designers need not only read minds (and forums) but know our hearts, make a game that we like, not what we claim to want. At times they succeed, at time they fail. Not an easy task.