Because you're the kind of customers Google wants. Not because you're paying for a service, but because you have shown that you want to pay for a service, which

Because you're the kind of customers Google wants. Not because you're paying for a service, but because you have shown that you want to pay for a service, which they can otherwise show for free with ads. You're the kind of customer advertisers want to see their ads blasted to. And trust me, while Google may not have ads for you now, it will happen eventually - and you won't see it coming. Heck, they might already be serving you to the advertisers in other ways.