because back then the groom never saw the bride in person before the wedding. he could call himself lucky if he got a small painting. of course the bride got nothing because - nobody cared at the time what the bride had to say - anyway. sometimes it happened, that the groom left the bride standing at the altar because he didnt like how she looked in real life. so they invented the veil as a tradition, so the groom would see the face only after they were married. divorce didnt exist, so he was stuck with the bride. again, nobody cared about the bride .....
I always have to cringe if a bride wants to wear a veil even though she doesnt know about the origin

i wanna see he flipped the veil and kissed after the vow