Why do brides dress the way they do?

I used this video a few days ago. But I want to look at one particular part of it: a wedding 2:40 into the video. The bride is wearing a strapless dress. I have seen brides dressed in this way in different countries. It always embarrasses me because I know that most of them would never go to Mass on any other occasion wearing a similar dress. Why do they dress this way on one of the most important days in their life?

Irishman Percy French, one of the first persons I hope to meet in heaven, wrote Where the Mountains of Mourne Sweep Down to the Sea in 1896, a song I have been known to sing on occasion. One of the stanzas goes:

I believe that when writin' a wish you expressed
As to how the fine ladies in London were dressed
Well if you'll believe me, when asked to a ball
They don't wear no top to their dresses at all
Oh I've seen them meself and you could not in truth
Say that if they were bound for a ball or a bath
Don't be startin' them fashions, now Mary machree
Where the Mountains of Mourne sweep down to the sea.

I wonder what he would have made of church weddings today!