TOS wasn't always so "enlightened". They characterized hippies as too dumb to live. Or where Kirk actually thinks he's a Native American (that was just awful). Or the episode where Kirk and a woman exchange bodies doesn't exactly shine the best light on women in command.
OK, I agree. Now what?
What everyone else is saying. What really defines Star Trek? To me, it's how the characters deal with the challenges they face. It's not the size of the screen, the explosions or even the villains. It's what the characters do and how they act.
Do I believe these people playing these iconic characters? Yes.
Can I relate to them? Do I care what happens to them? In this case, yes.
And was it fun to watch? Hell, yes.