I wouldn't do a wedding for all the tea in China.
I do parties and corporate stuff though.

Weddings bring out the worst in people.
I guess that brides especially are very nervous and want the very best for the day and posing for photos is just a hinderance to them as they are so worried about a myriad of other things that photography is the last thing on their list.
They figure that they are spending good money on the tog, so he/she HAS to do a great job regardless.
Brides have so much to think about on the day and don't want the hassle of having to actually stop and pose, because they THINK that they have to look after every little thing about the wedding and reception.
I think it's rare that a bride can actually relax and enjoy their own wedding as most weddings are about showing off to their friends and family at how much they have spent and how much trouble they went to.
I've been to a number of weddings where they have spent tens of thousands of dollars on the wedding to make a big show, when they could have really used that money to put a deposit on a home, and I guess that would make me nervous too.

I pity wedding togs, I really do.
It's a very tough job.