I'd like to suggest to be implemented the following change to event NPCs: Make them so you can trade as many Items as you have what it needs at once, instead of having to click many and many times for each exchange. Mr. Sandman, for example, has 5 chat windows for each trade, it means you have to click 6 times (either with mouse or key binds) everytime. This event is too late for a change, but I hope Devs do remember this for the next events.
Some more specific information about the "keybinds" mentioned by OP. Stand next to the NPC and press "NPC chat" to talk. Press "Y" to choose "Yes" in a yes-or-no chat window. Use up or down arrows to highlight an option in multiple-select chat windows. Press "Enter" to select an option in multiple-select chat windows, and advance all regular chat windows. Using these shortcuts, exchanging an item from Mr. Sandman is "NPC Chat -> Enter -> down arrow until you move to your desired item -> Enter -> Y -> Enter. Still takes a bit of time, but much easier than clicking. But yeah, I agree with this change.
Put all the future event NPCs on the ship between victoria island and orbis so people will actually ride the darn ship!!! Plz don't hit me~~~