Oh, I can definitely understand it for announcements and suchlike.
Display - hmm, that must be a personal thing. If I try out something and give it to DH and it doesn't open so that he can set it somewhere free-standing, for him that's not a "real" card, and there are quite a few of the tutorials here where I often mount what would be a "flat" card onto a regular card base.
Funny, too, because my ATC collection is much more prone to blowing down in a draught than the free-standing cards on almost every available surface in the sitting-room.
I guess also that because I usually write in ones I'm sending to friends, I like the space. And personally, if I pick up a card on someone's mantelpiece, I look at the front and back (to see if there sany information or anything) but I'd feel I was being intrusive to look at the inside. That's just me
And oh my, when I read Joanne's post about the weather, that chimed so true. I've had some very wet and soggy envelopes come in to me, including a couple with footprints on them, and very occasionally a card that has got wet even through the envelope. So thank goodness for envelopes and the protection they mostly do afford!
Thanks for explaining what you meant by "not quite sensible" . Now I see where you're coming from!