I use them at work, I have the habit of looking at my todolist when I have nothing to do, or to decide what to do next. Actually we use a ticket system that could act as a todolist, but it's a mess for "local" reasons.

This remembers me that tickets systems are just glorified todolists - and maybe they suffer from the same feature bloat as todolist apps. Although I acknowledge ticket systems are team tools, so it is a whole different game.