Well technically it's on a boat moving through sand, and you rarely actually fight him. You just kind of pester him with cannonballs until he falls over. They haven't mentioned any of this because Airships aren't even in the game yet. First they're implementing it as transport yes but they haven't said there will never be large battles. Why announce content the game isn't even ready for?
Except they have said they are eventually going to do mounted combat for specific encounters.
They've stated that things like hamlet defense haven't been forgotten, they're just put on the back burner for now since fixing the game's core systems kind of comes first.
On the OP suggestion: I think involving crafters in battles is good ONLY if done properly. As was stated previously involving crafters in battles is what got us the sad excuse for "battles" in the main campaign. Honestly though most of the suggestions involve simply repairing. Why not have them build things, possibly when group crafting is implemented? Doesn't even have to be set stationary objects, they could allow crafters to build and place cannons or other traps mid-battle. These things would probably only be for that specific battle or those large battles just for the sake of balance though.
