"We like to think that the ones spending vast sums on these games are sons of Dubai oligarchs, but we have the data to prove that they're not, and that they probably can't afford to spend what they're spending. We're saying our market is suckers - we're going to cast a net that catches as many mentally ill people as we can!" ~Nik DavidsonAre some cash shops predatory? Yes. Are many sub games skinner-box grinds designed to milk monthly fees? Yes. Are there some people who should probably stay away from any game (sub or F2P), because they can't control themselves (either time or moneywise)? Yes, but whose job is it to police those people, the game company's?
Should games (or laws) put limits on how much money a player can spend in a F2P per month? What kind of mechanics can drive 'too much' spending (are they the same mechanics that, in a sub game, encourage 'too much playing'?), and how does worrying about people spending large amounts of money conflict with the 'A few big spenders pay for everyone' structure F2P games are built around?
And what even IS the monetary definition of a 'big spender' in a F2P game? 20$? 1000$? I've heard that only 5-10% on average in any F2P game spend money, and the definition of 'the average big spender' is a lot less than you'd think. But there is still very little public data about this (at least in English) that I could find.
There's also this fact to consider -- F2P originally arose in Asia because of the extremely high software piracy rate there (in other words, selling a box would be financial suicide), so from the start there has never been a 'baked-in' requirement for a cash shop-model game to be exploitative or a cheaply-designed money pit rather than a quality game. A F2P game can be both a good game and have a fair cash shop.
There is a real need for legitimate debate about what 'fair' monetization models for F2P/Freemium games are. I think that it's hard to pin down exactly, because no two games (or cash shops) are the same. I think the Western MMO market is still trying to figure this one out.
Related Reading: F2P is Not Exploitative
Free vs Pay Games [DICE 2011]
$100k Whales: Intro to Chinese Browser Game Design