[lev99]

The people that can afford to pay and do not is a less valuable population than the people that can afford to pay and do.

Edit: valuable from an advertisement point of view.

[Dragory]

Indeed, which is how we got into this comment thread to begin with. Personally I'd gladly pay to hide ads in services I use frequently, but that also makes me more attractive to the advertisers. Fortunately most services that I use that have an ad-free option have also kept it ad-free, at least for now.