Variations on "Well I paid for my honeymoon myself" miss the point as far as I am concerned.
Did you pay for your own casserole dishes, sheets, towels, china, crystal, candles, picture frames, etc. as well? If a couple would rather pay for those things than for their honeymoon, I think it's awfully narrow to call that tacky.
Serving bowls cost money. Swimming with dolphins costs money. Both will be treasured. Why is it tacky to ask for one and not the other?