We did this, I only buy pyjamas for this if they need them anyway so didn't last year, and toothbrushes and bath stuff usually go in the stocking so ours was:
Christmas mug (same every year) with hot chocolate powder, marshmallows, sprinkles in a jar for ds to make up.
Christmas biscuits (homemade shortbread)
Christmas film for us all to watch
Christmas book (Night Before Christmas usually, as read lots of other Christmas books in the run up)
Reindeer food (oats and glitter)
A new Christmas decoration each for the tree
CBeebies Christmas mag
Slipper socks
And their empty stockings!
I like some of the ideas on here about including Christmas crafts etc. I may well do an advent hamper too this year, because mumsnet made me as usually I'm really disorganised about doing craft stuff and never end up doing as much as I'd like, it sounds like a good way to get all the bits you need together and getting it all sorted in time.
I think it's lovely that people put so much thought into making it so special for their children, I don't see any vulgarity. From reading these lists, it is all stuff which people would have over the Christmas period anyway, just shoved all together in a box with pretty paper.
It is spreading out the enjoyment of things, rather than stuff for the sake of stuff. For instance, my ds loves the Christmas magazine, doing all the stickers and activities, but he wouldn't have time to do it if he got it on Christmas Day, there'd be too much else going on. Reading other people's, most things are things you might put in a stocking, but they get taken more notice of when brought out the night before, when kids just want to get excited about something, even a new flannel will do the trick.
Christmas Eve here used to be a mad rush getting everything baked/wrapped/delivered, but now this gives us a little hook to hang the day up on and makes sure we're all settled down together enjoying it and helps the children wind down before bed.
Christmas is when it is to be a midwinter festival, something to brighten up the darkest months of the year, so drawing out the celebrations past the one day makes sense to me.