Ready is essential to combat the likes of shadows and wraiths that move in and out of floors and walls, plus swooping flying creatures. Otherwise you can't target the former and can only do ranged attacks against the latter.
Not a problem if you don't have truly flying creatures in your video game!
Or in general change the abilities of creatures that'd otherwise rely on PCs readied actions to defeat (e.g., Phase Spiders).
There is no reason Dodge shouldn't be in BG3. It's a core action.
Ready is a bit more difficult, but with the reaction system in BG3 it should be relatively simple to add at least a basic Ready functionality. I like the suggestion above that essentially you can use your reaction to Delay.