You'd be surprised at how many of the tasks are BS-y when changing the world.
Of course, a good boss will try to explain why the tasks he is assigning are important so the employees will see value in it too. Sometimes that is not possible. For instance, perhaps the reason behind the task involves sensitive information that cannot be released (this comes up very often in the military, and occassionally in corporate jobs.) Perhaps there just isn't time for the explanation right then. Or perhaps the employee just disagrees with the explanation when given.
In those cases, a good employee will get the project done well whether or not the employee sees value in it because the boss/organization does see value in it. An employee that does not do that should and probably will be fired with cause.
Apparently someone once thought over-designing the O-rings on the shuttle was BS work.
Frankly if something isn't BS, the reason can be properly explained. And if the subject can't understand the reason why, then he/she is not ready to do the work.
So whoever over-designed the O-rings must have had a good reason to do so. If he/she had a good reason, it is by definition no longer BS (it may still be boring grunt work). If not, then they were just lucky that it worked out.
"Grunt work" that you learn from or that sets you up to do more interesting work is not so bad. If you build a city, you need to maintain the sewer system. If your company has you maintaining 8 peoples' cities because you're young and expected to pay dues, you should get another job.