if people choose to give money as a gift, i'm sure the couple would be just as happy, but to outright ask to help contribute for the wedding, very tacky. in my grandparent's country they ask people to be 'godparents'for the cake, dress,rings,music, etc. very low class. when i was getting married, my future sister in law asked, after we asked her to be in our wedding, 'what do you want me to be godparent of?'
i said 'nothing, nevermind, i have changed my mind, you're out. i find that insulting of you. we wanted you in our wedding, to be a part of our special day, that was not the reason i asked you. bye.