A theory should be as simple as possible but no simpler.
Of course we can generalize this : "an X should be as at-the-limit as possible but no further".
Einstein principles are magnificently meaninglessly tautological and banal. But have some kind of interest because they can focus your thinking on what "as possible" means.
For example. I'm pretty sure that 100% of humans in the world accept the political Einstein principle : "people should be as free as possible but no free-er". And that 99.9999% of them will accept the substitution of "as possible" with something like "as they can without harming anyone else". All the differences in political opinions and positions can therefore be understood as a differing beliefs about what constitutes harm, and how responsible you are for it.
A libertarian has a narrow view of harm limited to obvious physical violence. A conservative will see harm in unorthodox behaviour which corrodes social norms and cohesion. A feminist will see harm in speech and images that propagate demeaning and disempowering myths about women. A socialist will see harm in taking advantage of differentials in power and wealth when striking a bargain. A patriot will see harm in criticising their country. A green will see harm in anything that accelerates the deteriation of the environment.
Other Einstein principles :
Tax should be as low as possible but no lower.
A program should be as scalable as possible but no more scalable.
See also :