Moral behind marriages - love?

Yesterday happened to attend a 'love-cum arranged marriage' of a relative. It was a first for me for many reasons.
1. The girl was from a different state (Kerala). The guy is our relative (Tamil). Both of them are working.
2. The girl's family didn’t turn up or rather..they didnt know
3. The guys’ family had arranged for the marriage in a very happy manner with out any ill feeling of being compelled by their son
4. The marriage was held in the Groom's house with all the "dhada pudal" associated with a typical South Indian marriage.
5. Only the near & dear were invited which could easily mean there was a crowd of 50-60 people.

After marriage, the bride's family was called up to inform that the marriage had happened. They had earlier refused all discussions on the marriage topic. After a six year wait, the couple decided to move on.

We came home after a sumptuous meal. Something kept on nagging me...

Was the happiness of the marriage complete without the bride's family's blessings?
If the bride's family had also accepted the marriage, it would have been one gala evening of festivities, But…they chose the other way.
The guy is from a good family, works in a good company..more than that, their daughter loves the guy & they have been going around for the past six years.. so 'infatuation' argument is also ruled out.

I'm left to wonder, in these times of globalization when marriages across cultures are fast happening, what makes the parents so rigid. I can safely say "ego".
Most of the parents do a turn around after a year or two, & accept the marriage. Why not before?