I think wedding gifts have gotten ridiculous. It seems like in most cases, it has become an expectation that you should receive something, or in the guest's case, that you should gift something, regardless of whether or not anything is needed, and it's just strange, TO ME. I know others won't agree with me, I'm just stating my opinion and not trying to indicate that everyone should agree.
Wedding registries, to me, seem like they should be for practical things that a couple has a need for when starting a life together. If they don't really have a need for anything because they've been living together for a while or already have the essentials, then I really don't see the point in registering. I find it odd that grown adults are registering, and in general EXPECTING to receive large gifts (whether physical items, cash, donations to honeyfunds, whatever) from a bunch of wedding guests that usually include distant family, old co-workers, etc. Many people that you wouldn't give birthday or Christmas presents to and wouldn't receive those types of gifts from. It seems like because traditionally couples didn't have much starting out and needed a lot of the essentials, that practice has carried over and expanded for those that get married and don't really need the gifts that were traditionally given. Now it's the expectation that I don't need household items, but couples get gifts when they get married, so give me cash or donate to my honeymoon. On the other side, it's well, since gifts are always given when people get married, then as a guest, I have to give something, even if they don't need the essentials.
I think it's great if people want to give cash or donate toward a honeymoon or whatever, but it does seem to be like an expectation nowadays that guests should give you something for getting married. That's where registering/asking for gifts towards a honeymoon or other luxuries fits into this for me. It's like saying we don't need anything, but I know you're still going to give me something so here's what I want you to give me. There's that bit of expectation in there, even if it's not what the couple is intending. If you register for just what you need/have no registry, then guests can still decide for themselves if they wish to give you cash or whatever else once everything on the registry is gone, but it seems less like you're expecting guests to give you something and more like you actually just want to celebrate with them.