All of the Treks – with the possible exception of Enterprise – had a wonderful schizophrenia about their tone that is very rare on television today; you would never really know, tuning in, whether you were going to see a drama or a comedy, or whether the drama was going to be of the “This is an allegory for a real-world situation and we shall all be making a Very Serious Point” variety, or the “We’re trying to make a suspenseful thriller, so expect long looks punctuated with stirring soundtrack strings” one, or even the “Want an action movie in less than an hour? We’ll do our best, but don’t judge us too harshly” attempts. What was weirdly wonderful about Trek was the play-of-the-week nature of the show, even when there were longer-running continuities running through episodes, and television – especially genre television – has lost that variety; normally shows stake out their tone early on and stay there, hoping to ensure loyalty through stability and knowing exactly what you’ll get when you switch on.
I think they’re generally right about tonal consistency, though something like Community does veer from being entirely goofy and surreal to fairly grounded and human, so it’s not entirely impossible. And I think with Star Trek, it’s easy enough to solve: have each season revolve around a long-arc mission and all of the things that happen along the way, some of which will be serious, some of which will be goofy, all of which will offer opportunities for different tones and different points — in other words, make the show like Buffy. But I actually wonder if the Very Serious Point bit, the optimism about a progressive, secular, interconnected vision of the future might actually be the bigger challenge for networks that are either skittish about politics or committed to a gritty, pessimistic take on them. I would love to see a network show (as opposed to a cable network like Showtime or SyFy) have a major character on a show who is a rehabilitated extremist.