"I will never buy such a product".
That's the point. You may not have to. If, in exchange for watching a few advertisements a day, consumers were given a shiny new Apple iPhone300kTurbo for "free", or were given "free" cell service, that might be seen as an acceptable trade.
It benefits Apple by giving them evidence that those pricey advertisements they sell are reaching eyeballs.
Pure speculation on my part, btw. I have no inside knowledge (nor do I really care) about Apple's marketing or product plans.