I had started to find my contexts useless for the same reasons listed in the OP. Every next action was being labeled @computer which was becoming meaningless. Then I changed my contexts to suit where I actually wanted to do things and realized that though I COULD perform some actions at a computer at home or at work, I really needed to leave some things at work and not bring so many tasks home with me.
Contexts helped me decide in advance to STOP working when I leave a context, rather than helping me to STARTworking when I enter a context. Workaholics like me may find contexts useful after all.