Having your fiance wanting a diamond ring is a different problem then your mother in law pushing you to spend 30k on your wedding to show off to the neighbors.
Advertisement based spending is just another set of problems when it develops without outside social pressure. Its the difference between your wife needing to show off to her mother and girlfriends, wanting to show off. or you two agreeing about how it might be spend best.
Just to point out though, while the example of diamond rings is focused on the female spouse, this isnt a issue that only happens with her. Pick another example and you could switch the roles.
The last option, of discussing how to spend the money, is simply about the state of your relationship. If you two agree that spending 30k is worth the fun of taking a few month off for vacation, all the best to you. Just do it because you want to, not because you think you have to.
(I agree with you).. but back to the original commenter's point about the behavior, versus the object of the behavior:
Do you believe that eliminating (or sufficienctly discouraging through education or contrary social pressure) diamonds and/or expensive weddings would sufficiently eliminate this spending above ones means? Or would that spending just shift to other targets, such as different jewelry (which even the article refers to in talking about spending more money on setting instead) or experiences?