Replace “principle” with “scientific theory.” Why shouldn’t principles be subject to tests and criticism?
Also, if your principles are likely to change quickly, it's probable that they haven't been thought through very thoroughly to begin with. It's not like you have to wait for situations to actually arise to consider them.
As a tangent: while the parallel to scientific theories is good on the surface, it does lump in this idea that there’s a universal set of correct principles. Isn’t that just philosophy, then? Logical arguments about which principles are sound & universal. Maybe the lesson is to pick principles from the battle-tested ones rather than trying to develop your own.