Even if they remember the big picture, the tyranny of the sprint deadlines make it impossible to take the big picture into account - whatever gets the task done faster, no matter whether or not it creates problems down the line.
If your regularly running against sprint deadlines something is broken in either your planning or estimates. Either your trying to cram too much into a sprint or for some reason your regularly estimating tasks as significantly easier than they are.
I'll also note if the response to an underestimated task is "well either pull some extra hours or rush it to get it in anyway" an important step of scrum is being missed.
