How many fields obscure the form of payment, the amounts, the methods when you purchase a good or service? You're oversimplifying and glossing over the real issues.
If it was as simple as "you must pay" and nothing else mattered, then any form of payment would be justifiable.
At the same time, if you have ever been in certain neighbourhoods, you personally might feel really grateful for keeping this setting on; a few hours, or days, in some places can send you ads that'll change your ad profile SO much for SO long, it'll drive you crazy if you aren't careful, or at least make you annoyed and regret it.
Personally, I prefer variety in my ads, and not to be profiled, but there are times I specifically and expressly choose tracking for ads.