A few random thoughts i've had on the subject, (and some ideas...)
A problem I see is that we kvetch and kvetch about the the financial pressures...
...but when people try to provide concrete (and, yes, drastic) solutions... they get shot down as unworkable, unfeeling, unfair...
(and I refer people to the responses on the first few pages of the ST war thread to suggestions that somethings like simchos be toned down...)
The only way to get anywhere is going to have to be by dashing peoples current (unrealistic!) expectations and dreams. A little bit upthread someone suggested having the chassan and kalla pay for the wedding would reduce the expenses greatly. This is so true! When I was getting married my kalla had her heart set on a particular thing that both sets of parents agreed was a bit much, and a teachable moment, so they told her "If you really want it, we'll do it for you, but if we don't do it, we'll give you the money it would have cost..." ... She took the money.
People cant say no to themselves, how can they possibly be saying no to their kids? (and we're now on at least the second generation of this!)
People currently making their parnassa by providing the community with luxury level services (or luxury level prices...) do not have the right to push against comunity takanos by saying that we will be hurting their parnassa. Better for these people to have to (re?)train for some other field than to be able to endlessly hold the financial gun to everyone elses head. (anyways, industries change, jobs become obsolete is a fact of economics).
A couple of ideas that are a fact of life in many Yeshivish kehilos in EY, that really should have little issue being imported to the US.
Classmates do not go to the (fancy?) Bar Mitzva seuda at all. (first cousins may go). Also not to the Aliya on Shabbos (unless they live really close by, like daven in that shul anyway). Theres a seudas chaveirim in the school during school hours, with a more or less set menu, and the school tries to combine a number of celebrations together to reduce costs and distruption.
Schools can take a stand against financial competetion anong the students. (I know, harder than it sounds). My is in a cheder with a vast spectrum of financial abilities (like some people are likely can spend on a single shabbos a sum that is others entire months budget). The school has very clear rules: No branded apparel starting in Third grade. We will not let anything become a financial competition, if we see that something is becoming so, we will not allow it in school furthur.
It has to become acceptable again to make truly pashut simchos. Not the Takana lite style thing now seen as the simplest thing possible, truly pashut simchos - just to move the overton window of acceptable simchos back to something reasonable.