An idea for seige towers

Currently seige towers are probably the most unused unit at all levels. I was thinking and it occurs to me that it's not because of their cost but because they are not functional. I would propose seige towers to have 4 buttons:

1) Attach (right click): if you right click a wall segment that's where you want your seige tower to go by taking the closest route. Needless to say you can only attach to wall segments.

2) Fix: this command makes your seige tower immovable so anyone trying to garrison has to come to the tower and the tower won't move

3) Unload: unload all units on same side

4) transfer: unload all units to the opposite side.

Once you're confident that the 300+ odd resources you spend won't be a total waste, you're much more likely to use them.

There might be some concern that this makes them too easy to use in which case the fix button could be removed but the attach command is probably the most needed.

I know STs can potentially change game, and also there might be concerns about their bring over powered. There are ways to nerf STs, but dysfunctionality is not one of them I believe.

That said- I do have an idea to "nerf" them if that is indeed a big concern.

1) reduce garrison capacity to 1 or other low number. This causes them to require some attention.

2) less potent nerf- garrison capacity remains same but each unit has to be unloaded individually.