I agree. I love being a worker, but it'd be a bit nice if they gave you a bit more to do. Most maps don't have a ton of stuff to build out in the field so once you've leveled up all your hat machines, the catapult, and built what else you can you don't have a lot more building tasks left.
What I think it really needs is a benefit to capturing the towers. Some are secret passages, but most of them don't really do much. Yeah, it's a tall place to shoot from, but sometimes it blocks your shots. What about a mild healing/defensive/offensive field or something? Maybe even just the ability to respawn there? A lot of people have already reported that many games can take quite a while for someone to get the upper hand (or, well, the AI not being very good at working together to get the princess out) and it can be hard to take and hold the towers so some sort of benefit like this would help to keep the momentum going and give the controlling player a strong advantage. Right now aside from being a depot for workers to drop resources off at there isn't a lot of reason to bother in the mid to late game.