If there's anything they've grown to expect, and will be upset if it's missing, then personally I'd do it. It won't stop you adding any traditions of your own.
We'll be having Gdcs for the first time this year, but they're only 2 and 3, so too young for specific expectations, except that they know Father Christmas will be coming. I have some lovely 'Night Before Christmas' and Nativity books to read to them.
And I don't mind admitting that I ditched my 'not overdoing it' principles and bought a (cheap!) Father Christmas duvet set for the double bed they'll be sharing.
BTW I recently found a really lovely Christmas book for this age - 'Room For A Little One', with truly beautiful illustrations of all the animals in the stable - and we'll be watching The Snowman. Apart from putting out a snifter and mince pie for FC, and carrots for the reindeer, that'll be about it, though we might try some of those stained glass biscuits - they sound lovely.