What I find interesting is that these sterile neutrinos do not "badly broke" the Standard Model, instead they come as a complement and obey all the other princ

What I find interesting is that these sterile neutrinos do not "badly broke" the Standard Model, instead they come as a complement and obey all the other principles otherwise held for particle physics (symmetry groups, isospins, etc). On the contrary, as they are the missing right-handed neutrinos required to explain the mass of left-handed (i.e. "normal") neutrinos through the Higgs mechanism, it may instead come as a new victory of the explanatory power of the Standard Model.