Blind brands

I bought a leather bag today that wasn’t really cheap, and as I was paying for it, I was asked whether I also wanted to buy a specially formulated cloth that would protect it from day-to-day scratches and the like, for an extra £2. I did, but it got me thinking: if the brand had given it free instead, they would have earned a lot of goodwill at no huge cost to them. If it is profitability they are worried about, then they can just as easily build the cost into the product, which I’m sure they are doing anyway, to some extent at least. I don’t understand why some brands refuse to get it.