I guess they just don't want to add the ''dodge action'' for some reason, it just a simple action with a simple effect, I doubt it's difficult to add into the game at any moment wich is kind of weird and confusing to me.
They added it for the monk as one of its second level features -- Patient Defense.
"Attack Rolls against you have Disadvantage and you have Advantage on Dexterity saving throws"
From the FextraLife monk video Time Stamp 7:36 (Don't watch the full video if you wish to avoid spoilers)
For the Monk it costs 1 Ki to 'Dodge' as a bonus action which is the same as it is in PnP 5e. So we know the coding for Dodge exists. Seems like it would be an easy win to include it.
