I think it'd be a good thing to do. You have a process in place, and enough self discipline to avoid installing such apps. But not everyone is like that. I'm guessing majority of the users go like this: "ah, it's a free app, great, I'll get it. <10 mins in the game, when they run out of gems, bullets, whatnot> Oh, what do I do now? £0.99 is not too bad, I'll just get another pack of <blah>, so I don't have to wait 30 mins".
Can people self-regulate and avoid behaving like that? Yes. Do they? I doubt it.
I'm not the first or last person to say this, but the solution to "some people behave in way X, while other people behave in way Y" is generally not "we need legislation compelling everyone to behave the same way".
No, but to draw an analogy that is actually vaguely close to what we're discussing, if some people behave in way X, which is not good for them, or for wider society, we need legislation allowing them to avoid behaving in way X. Yes, that example is exaggerated in the opposite direction from, but far less than, yours.
In the first place, the concept of "legislation allowing [people] to avoid behaving" in a certain way is incoherent. Say what you mean.
In the second place, the concept of "we need to prevent people from doing anything negative to themselves" is not distinguishable from the concept of "where there are multiple ways for people to behave, all but one must be prohibited". In fact, it's not even distinguishable from the concept of "where there are ways for people to behave, all must be prohibited".
No one is suggesting to ban anything, or enforce people's behaviour in any way. What they want to do is to enforce correct labels on items that people are purchasing. If it says "free" it must be free full stop. If it is only partially free, then it must say so.
It's like getting a "free" train ticket, but then when you want to travel you're asked to pay for boarding the train.
Can people self-regulate and avoid behaving like that? Yes. Do they? I doubt it.