Does tower height matter?
Solution 1:
tl;dr Towers increase range compared to walls.
While being attacked by a fairly small Siege Camp army from the NE & SW, I noticed that archers in towers on the NW & SE walls were shooting while archers on the nearby (closer) walls were not. Lookout Tower added about 5 squares to the range. There may be a small (1 or 2 squares) range advantage with small towers over lookout. Attack vectors made comparison between tower types difficult. I have not researched larger towers as of yet.