I just don't understand why brides do this - or perhaps I do - they want to look the best on the day - so if you got ugly knees and wobby arms, all the better for her!!!
Seriously though, I've been to weddings where the bride was flexible and chose styles that suited her girls, I've been to weddings where they chose fashion over what suited and still have visions of the stretch marks on the roll hanging over the top of a very tight strapless gown on one of the bridesmaids which clearly didn't suit her shape. I mean the girl couldn't help that but someone with sense should've said something about a more suitable dress - might add these weren't off the rack but custom made dresses too.
I also work with someone who was bridesmaid to a bridezilla in Feb - which is not that long ago - and she has fallen out via text message with the bride too. She is kicking herself for ever agreeing to it to begin with.
To me, you should be able to look back at those photos in 25 years and still have fond memories and hopefully a friendship with that person - a dress is just not worth it.