It never tried to look realistic.
That's not really true. The producers--at least on TOS--expended considerable effort trying to keep the show plausible. Roddenberry reportedly consulted numerous experts (not to mention keeping deForest Research practically on retainer) on various futuristic aspects of the show. (Consultations that, IIRC, led to changing "lasers" to "phasers," for example.)
What they didn't
do was lose track of the fact that they were making dramatic entertainment, not a documentary.