A few things that have been annoying me lately.
First, dwarves suspending a task because of unique circumstances that only affect the person who was initially assigned to the job. Perhaps the worst case of this:
Aban Emathcatten, Mason cancels Construct Building: Seeking Infant.
The dwarves suspended the construction of Wall.
While this might make sense if the entire fortress suddenly decided to cancel every other task to help find her kid, since they didn't, it makes little to no sense to tell everybody not to work on whatever she was doing before she realized her kid was missing. Another example:
Kadol Cattensikel, Mason cancels Construct Building: Unconscious.
The dwarves suspended the construction of Wall.
This makes slightly more sense considering the dwarf was unconscious as a result of a structure collapse, and therefore it could be argued that the area he was in was hazardous, but since a given collapse generally only happens once... Oh, here's another one:
Aban Emathcatten, Furniture Hauler cancels Construct Building: Throwing tantrum.
The dwarves suspended the construction of rock Coffin.
Though to be fair, I wouldn't want to be anywhere near a tantruming dwarf either. It's no coincidence that he was building a coffin before he joined in the tantrum spiral. Even so, I would have preferred they cancelled the task when he actually interrupted somebody who was trying to finish it. And... Another one:
Sarvesh Sibrekatast, Furniture Hauler cancels Construct Building: Taken by mood.
The dwarves suspended the construction of rock Floor Grate.
Now, why would they cancel what he was doing just because he got distracted?
Sarvesh Sibrekatast, Furniture Hauler looses a roaring laughter, fell and terrible!
Oh... But seriously, for any other mood this would be silly.
Next, deconstructing buildings. I've had no shortage of named fish lately as a result of dwarves taking way too long to remove a constructed floor over an infested lake, and it's quite frustrating to have to start over again just because the person who started the process got eaten by a carp. I think it would make more sense, and be a lot less dangerous, if constructions kept track of how close they were to being destroyed.
This would also help for other interruptions, like dangerous terrain. It's just sad watching a dwarf desperately trying to break down the wall keeping him trapped in a room slowly flooding with water, and then running away because his legs got wet from an unusually deep wave, only to start over because the wall magically repaired itself.
On a somewhat related note, it would be nice if we could override the automatic suspension of tasks somehow, so, for instance, dwarves would keep working on that wall that will be the only thing between your fortress and endless flood water, no matter how many times they have to give up for a moment because the worker starts drowning or gets scared by a carp. Maybe a (q)-(f)inish at all costs command. Might be useful for workshops too, though the spam would get annoying after a while.
Finally, it's extremely annoying to have a dwarf die out of nowhere because he trapped himself while building a wall or something, and you didn't notice until it was too late. A 'Urist McTrapped is dying of thirst' alert message would be very useful, though obviously it should only be displayed when their status first changes to avoid a constant barrage of 'Noble McMandate is starving' when you trap them in their room intentionally.