Wow! I had no idea how misleading honeymoon registries are!
So in addition to my general feeling of how tacky it is to ask others to pay for your trip, there's the additional wrongness of taking a percentage off the top and not applying the funds to the requested item at all!
As for the importance of having a huge, fancy trip for the honeymoon, well I can only say my personal experience was that our honeymoon was beyond fabulous, even though it was on a tight budget. We spent our wedding night in a local B&B, then started driving north. We had a hotel booked in Vancouver, BC for two nights, but other than that we were free to chose the path we wanted and hunt out nice but inexpensive places to stay along the road. We checked out antique stores, stopped anyplace that looked fun, and had a fabulous time. We had a total of about two fancy meals, built up a store of hilarious stories about hotels both good and bad, chatted with random people we met along the way, and generally had the time of our lives. No, we didn't swim with the dolphins, but the octopus at the Vancouver Aqaurium danced for me after hiding most of the day. We didn't get a couples massage, but we had a nice chat with a pleasant transexual in a hobby shop in the middle of nowhere Oregon. I adored spending quiet time with my husband simply seeing whatever there was to be seen.
And when we took our dream trip to London six years later, we had a blast on that one, too...and paid for it by ourselves.
If the couple has everything they need, give them a basket of gourmet foods, a pair of pretty champagne flutes, a special ornament for their first Christmas tree...there are so many options that nobody would ever register for, but will add to the HC's life in delightful and unexpected ways. As long as the couple isn't inflexible and the guests exercise their imagniations, there's always a wonderful and fun way to please a good friend or a relative.
But paying for someone's honeymoon through a register...not in a million years.