Tacky beyond belief and no better than a Go Fund Me site hitting up people to pay for your teen to go on "the trip of a lifetime" so you don't have to part with your own cash. On some level, you KNOW it is tacky or you wouldn't have asked, IMHO. I think what you are really wondering is, have standards slipped so much that people will just shrug and go along with it? Well, some will and some won't, but it will still be tacky.
It is YOUR honeymoon. YOU pay for it. If people choose to give you money as a wedding gift (unsolicited) then you can use that to help with the honeymoon. But you don't ask people to pay for something that you should pay for. It doesn't matter that you have lived together for years and have all the household stuff you need. That was your choice.
It costs almost nothing to go to a JP and get married. People choose weddings and honeymoons, which cost money. Their guests should not be responsible for those choices. They should not have hints dropped that cash gifts are best. Again, if someone chooses, unsolicited, to give you money, then do a happy dance. But to do otherwise is tacky, no matter how many people do it these days.