Are we discussing yet why the same Rebbes who enforce takana weddings for their Chassidim hold 7,000 person weddings for a grandchild every two weeks?
Sounds like you were waiting patiently for this
so let's tackle it. This is my opinion.
There's a difference between making a super fancy wedding and a wedding with a ton of people.
Chassidim want these grandiose weddings for their Rebbes children and grandchildren. Even those chassidim willing to forgo luxury weddings want them. Its their form of entertainment and they really enjoy it - I do too in the event that I attend such a wedding. Its not really considered a luxury wedding - you get some water, gefilte fish, and a chicken drum stick, not what one would call a fancy wedding by any stretch of the imagination.
Its just the scale of the population at the wedding that is grandiose and far surpasses the number of guests any wealthy wedding would manage to pull together.
So I'm not sure this answer will satisfy you, but this is one of the reasons these weddings continue to take place. Maybe others can shed light as to other reasons.