You’re right, "I hope you’re happy" makes sense in this context.
A similar expression in English would be "asking for it" as in, "you asked for it!" or "you were asking for it!" when talking about something bad.

"Vous l’aurez voulu" is a kind of "prophecy" that means that the one who takes the action, who is "vous", will have to face bad consequences he is now denying though he’s been warned. One could also say, in that situation: "tant pis pour vous". The meaning of that idiom is the future’s variation of that other idiomatic expression: "bien fait pour vous" that holds the same idea about the present or the recent past, now that the bad consequences can be seen.

Given someone or a group of people that have been persisting in some line of action which they have been warned repeatedly not to follow as otherwise something bad would happen to them, this expression is a way to signify to them that the person speaking is giving up on trying to help them to see the truth and that he/she will either take action in the way of submitting those people and that he/she is discharging him/herself of any responsability, and finally, if not involved in the process of this ill line of action, that he/she is discharging him/herself of any responsability (such as informing them, and helping them to get back on the right track).
A similar formula is "Vous ne direz pas que je ne vous l’ai pas dit.".
In other words it is a way for X of telling those people that what has been done to warn them is sufficient and nothing else will be done because it is more or less obvious that they are not listening.

The best translation seems to be "You have only yourself to blame." (Harrap’s dictionary, 1980); an answer that precedes mine, that of user spaghettibaguetti, provides a translation that appears to be more or less equivalent; it is "You asked for it.".

Therefore, it seems that a standard idiomatic formula has been misused to mean something else; perhaps it is a nebulous double meaning.