The siege towers are rarely seen. Actually, I bet most players never produced one.
It costs 200 wood, 160 gold. That is more expensive than a ram (160w, 75g) and a mangonel (160w, 135g). And it doesn’t attack. It is mostly used to unload an army over a wall, and in later game can be just forgotten, making them a very short term unit.
Compare it with a transport ship, which costs only 125 wood, no gold. The Siege Tower costs 200 wood and 160 gold. This seems ridiculously expensive compared to its use, and you obviously can’t even reload the units once jumped from wall.
It’s mostly used in Arena, but it seems more interesting to destroy the wall with the Saracen bonus, or with Arambais, or just petards and onagers, than to invest so much resources into a Siege Tower (where you also leave the wall intact and cannot return to the other side).
Then they have huge limitations such as, obviously not being able to reload army that was previously unloaded on other side of the wall, and not being able to carry any cavalry.
Siege Towers’ too high cost for what it gives has been discussed numerous times but I wonder why there have been no changes to see them more used in the game.
The fandom states
It has been described as being the “most useless” and “weakest” unit due to its very limited use of tactics, being a ‘one trick pony’, and high price.