You're probably only twenty years old and don't remember a time when there were only three networks and television went
off after midnight. I grew up in the Oakland/San Francisco Bay Area and was lucky to have an independant station, KTVU channel 2, and a public broadcast station, KQED channel 9. Most communities were not so blessed.
Star Trek was on the air about the same time as That Girl*, Petticoat Junction, Mr. Terrific, and a host of other shows that you have probably never heard of. Good television was RARE!
Star Trek was spectacular! Yes, for every "City On The Edge Of Forever" there was a salt critter episode. For every "Amok Time" there was the Al Capone episode. For every "Space Seed" there were Chinese people on another planet who were over 1,000 years old in a show set 300 years in the future.
Star Trek is that rare gem, like 2001: A Space Odyssey that is enjoyable 30 years after production. Say what you like about the space hippies episode, but understand that when you try to call Star Trek as a whole a "turd" you display your Anonymous Cowardice and ignorance.
* I actually enjoyed That Girl and would probably watch reruns if I knew when they played.