Legend:
Suggestions Ignorable natter
Well, all traps I've seen all have a general thing I've seen considered a problem: Even in the case of complete failure, no dwarves are hurt by the failure itself. For those who want dwarves to have a chance to die (in combat, typically), this safety is not acceptable.
Now, you could, say, hurt the mechanic who set up a simple trap when the trap fails, but what dwarf should be punished when the drowning trap is found to not work on the troll? When some goblins manage to survive 10z fall to a featureless pit?
Besides, it seems rather gamist when the visitors don't have capability for voodoo - in fact, I'd go so far to say to suggest
a dwarf should either see their masterwork being destroyed or gone from it's permanent place to suffer the travesty of an art defacement, or at least get some more information than a bad thought from it if they are to have telepathy with objects. Yet, I can't see simulationist way to have random wolfs hurt dwarves through walls, so for those players I'd guess only good traps would be non-existent, nigh-useless (at 10% chance to escape per movement the creature would have ~2/3 to escape before a dwarf from 10 tiles away can reach it - but it could stagger out the siege a bit, I guess) or prohibitively expensive (see non-existent) ones.
On the trap buildings as they currently are, though, second factor in their considered overpoweredness is their ability to deal with threats:
First, they'll hit anything not smart enough to avoid them - for all but repeating spikes, this means knowledge to not step on the well-hidden plate. Liasons can give that knowledge, but I'd suggest that individual units smart enough* should learn that too if they see someone being hit by one for that particular trap.
Stone-fall trap: Simple to set up and can injure any slow and relatively stupid being that passes over them, but require resetting after each use.
Cage trap: Deals with any single animal, requiring a new cage for each threat (or emptying the cage and killing the threat in another way, but that is far more complicated). Is the only way for dwarves to tame wild animals.
Weapon Trap: Can injure and sometimes kill multiple animals, but will eventually jam.
Spear trap: Deals with any number of threats that are over it when triggered, but requires some sort of repeater and the 40 step delay makes catching of a moving target more difficult. Additionally, can't be avoided by knowledge.
Here, to me it appears that while Stone-Fall trap appears weak compared to everything else, every other trap is somewhat balanced with each other for your usual fleshy targets.
However, the big advantages cage trap has is ability to catch something hardly hurtable, like a modded-in adamantine wolf, certainty that at least single animal will be stopped instead of showing miraculous dodging ability, and ability to both have controlled live training and controlled training of life.
Here, I'd suggest splitting these roles:
Have the stone fall trap be capable of holding up far more stones, a floor or a wall - making it the "single-shot but very deadly trap", while the cage traps could be made to work like upright spears are currently.
This would allow for the capture of wild animals for the determined and attentive overseers while also giving stone-fall traps an use.
* Mouse traps always catch several critters if a pack tries to make home in my house, despite the OPness of killing mouses by just spending a minute to lay out or reset a trap.
Glass - only used for capturing aquatic creatures (ground creatures captured in glass cages have a 15% chance per movement tick for that creature to destroy the cage and escape)
...You'd start hitting glass cage you're in with your bare fists? Brave =D
But the above idea of using the material strength, like it is planned for armor...I like this a lot.
How about this:
Instead of Building Destroyer tag, have someone who has reason to destroy building get an option to attack buildings - including cage they're inside of - with success determined by combat system and likelihood of doing it determined by their personality.
So, using myself as an example I would almost never try to break out of a glass cage without armor, but if I had some clothing on me I might try breaking out of wood one, and should I have even a single metal item I'd try to break out of a metal one.