There are a few answers we could give to this question: e.g.
- sometimes we do if there are cool events
- we are techies
- we just do stuff when we want
- this is a national day not a world religion
- what would Elizabeth Bishop have done?
Being at our most Australian on these kind of issues, I can only add that it seems a shame if poetry pays the price of becoming more popular* by expecting total conformity.
Anyway if you like poetry days here is some information http://www.un.org/en/events/poetryday/
Is poetry more popular btw? when did that get decided?