I did have when he was 3 and 4. At 5 and 6 he got parts of it. He liked the tree and the school play and carols. He's now 7. He probably will open some presents this year as he did at his birthday a few weeks ago. He probably won't get excited by any of them, or play with them. He'll spend most of the time on a screen in a room far away from everyone else. Each year he 'gets' a bit more about it. He remembers a bit more about what happened last time.
If you think about it Christmas is odd. Trees are inside not outside. Toys are covered in paper, not available to play with. Lots of people come to the house at once and are noisy. We eat turkey when we don't any other time. We pull bits of paper and they make a bang. We set puddings on fire. Its a load of bizarre rituals.
I haven't even bothered to explain santa we have enough trouble explaining real things without starting on pretend ones.
We cross off days on a calendar to explain holidays etc. He can understand dates now, but wouldn't have at 3. He knows Christmas is on 25 Dec - but he learns it as a rule not as anything to be excited about.
Its natural to feel sad. Its part of who you are and your history that Christmas is supposed to be special. It is sad you can't share it. That you can't recreate the excitement you felt as a child and pass that on.
But I feel less sad each year, it becomes your new 'normal'. More and more I learn to see the world through his eyes and find myself questioning why we do these things anyway!
When he was 4 we gave hardly any presents, we spent the money on a weekend in January at Centerparcs and enjoyed the look on his face when he whizzed down the watersides instead.