In the U.S. in particular, there's strong respect for individual rights enshrined in the Constitution, and a key role of the judicial branch is ensuring that those rights are respected regardless of what the majority thinks. The majority cannot enslave the minority, for example, regardless of what the legislature votes. Nor can it deprive it of speech or free assembly, or guns, or a right to trial by jury.
if only it were so simple
aka leave it to the experts because the majority isn't qualified to make such decisions.