Even when the Constitution flatly forbids doing something – for example, prohibiting the free exercise of religion, or abridging freedom of speech or press – courts often weigh competing considerations to decide whether the “something” may be done, pleading that the meaning of the prohibition isn’t clear.
When courts require that different things be balanced, the only way to tell whether they have been balanced in the way the courts think they should be balanced is to go right back to the courts. So you can see why some judges would love balancing tests. They encourage litigation and make judges more important. They increase their power at the expense of the power of legislators.
This is a dangerous tendency, because courts are far less well equipped to balance competing considerations than legislatures are. That is the sort of thing legislators are for.
But wouldn’t this problem solve itself? The Framers expected each branch to be jealous of the power of the others, so one would expect legislators to use their checks to resist the judicial invention of balancing tests. One would think they would say that if it is really true that the meaning of a particular Constitutional prohibition isn’t clear, pinning its meaning down is a legislative, not a judicial job.
On the contrary, when issues are so hot that legislators are afraid to exercise their constitutional responsibilities for fear of what the voters might do, sometimes they even insist that courts use balancing tests. They are only too happy to kick the ball into the courts.