The KS1 parents aren't aiming to remove their children from the test. It's just a protest to make a point.
If this was a non-threatening test, I might agree. But it has been made into something else. There are other ways of knowing what children have mastered that would work better in this age group.
The balance was about right in the old system. Sticking a high stakes test into KS1 and expecting children to sit it under strict exam condition is ridiculous.. Particularly when some of the papers may well be significantly above the level of many of the children raking it.