I think the big difference is that historically, when people had big weddings with a lot of guests, it would be more like a big community party and probably a potluck.
The modern "standard" for weddings is much more akin to what you'd expect from ROYALTY, historically.
Instead of the community/family pulling together to support the couple and everybody making a contribution to the wedding somehow, the couple hires an army of servants to put everything together and the guests just show up and eat and drink, leave a purchased gift, and go home.
Edit: in reference to the royalty aspect of modern weddings, specifically to the white wedding dress tradition.
The whole white wedding dress thing definitely began with the upper European classes. In times when most common women only owned 1-2 dresses for work and everyday life, dark colors were cheaply dyed, and preferred because they did not show stains, and therefore could be worn longer between washings and replacing. Women would get married in their best dress, which was usually just the newest everyday dress.
The wealthier upper classes, however, would flaunt their wealth by having a special, light colored dress made specifically for the wedding occasion, to show they could afford the luxury of a dress intended for a single purpose.
The white color also highlighted the virginity of a high status daughter, in order to cement her pureness in marriage and therefore value to the nobility class from which she came and was also forging an alliance by marrying into. Her dowry was further proof that she was of value to whatever contract her family secured for her.
Edit: Also to add that the same dark color material applied to menswear as well. Darker colors hid bloodstains well, so the common man or even the noble man could look presentable on their wedding day, despite possible bloodstains from the hunt or from warfare.