Gianni,
There is a simple rule: "The PMBOK Guide is always right". (At least until you pass the PMP Exam.)
So for now, please accept the fact that according to the PMBOK Guid, Risk are on exactly the same level as the other competing project constraints and for the PMP exam your opinion (thought I admit that it has merit) has to step aside. For the PMP exam: risk is equal to budget, scope, schedule and all the other constraints and not "included" in them as you say. And no matter how hard you argue... the PMBOK Guide's approach is what you will be tested on.
However, it's definitely something worth discussing outside of a PMP Exam preparation forum.
Also: If you review 01.36 again, you'll see that we have 2 slides on which we discuss risk and give a couple of examples. But I agree that we could give a few more risk-related examples. For instance, if you lower your budget you have to cut back on activities. Often, risk-related activities are the first to be impacted by this, leading to an overall increase in risk on your project. I've made a note of that.
Until Next Time,
Cornelius Fichtner, PMP, CSM
President, OSP International LLC