While it is nice to help the couple complete their dreams, if the couple would like to have money for their honeymoon, so what, if they would like selection of products for their home or new home, so what. It's not even consider rude, It's rude that you're invited to a wedding, when you know how expensive weddings are, the couples were so thoughtful to think of you and invited you, You as a guest attend to a wedding without a gift shows poor class of respect, You as a guest think you can go to a wedding drink all you want, eat all you want, dance your heart out all you want, and eat your cake and leave, and say "It's a nice wedding, Thanks for inviting me, see ya!"
Don't you want those couples to treasure and cherish the gifts you got them? showing your thoughts, your caring, and your respect. I would want someone to like my gift that I gave to them, because it's something they will treasure for years and years ahead, and I do know how expensive weddings are also, So, show your respect and don't be a wedding guest bum.