I don’t think many of us normal folk, if I may say that, actively like having our photos taken. I’m not at all photogenic, but when I remarked to a colleague that some people always looked good in photos, his reply was “Yes, Maggie, they’re the good-looking people”. 
Of course the mother of the groom needs to be in a photo or two, for the benefit of future generations if nothing else. Not attending isn’t an option. You could end up with a family rift like the one in my family - the one that means I have never seen a photo of my maternal grandparents. It’s sad that I’ll never know what they looked like.