I think we can all have and voice an opinion.
However, whatever one’s own feelings are, it’s not up to us to decide what is and isn’t appropriate for a complete stranger’s wedding outfit.
Plenty of people marry in white, in full wedding dresses, in second or even third marriages and often have children from prior relationships as their bridesmaids or pageboys.
It would not be for me, but I certainly wouldn’t judge others and I too think it was a beautiful dress which she looked radiant wearing.
Good luck to them both 