These are good compositions, but almost all of them could have been
better if a flash was properly used, especially the indoor shots.
It's not just the amount of light available, but the color spectrum
of the available light. All of the indoor shots, where light is
being filtered by the windows, show un-natural color casts and many
have been oversaturated in post to make them look more life-like.
Here is a perfect
example:
http://www.jacobel.com/wwf/imagepages/image26.htm
Notice all the ISO noise and PS saturation artifacts. And the odd
colors of her face suggest to me that the artificial light was
flourescent, the prime ingredient in a recipe for disaster.
Also note the CA around her veil. Maybe it's just a crummy lens,
but another stop or two plus flash might have gotten rid of that.
(Actually, in this case, the CA could have been removed very easily
in PS by moving the blue channel just a bit)
I don't think there is any arguement about non-flash wedding photos
being POSSIBLE, and these are certainly decent photos given the
tools that were used, but if the wedding party will allow it I
can't think of a reason NOT to use it.