The classic episodes that everyone is supposed to know and love is a small fraction of the series.
Hardly surprising given that the series was on the air for five seasons, broadcasting 156 individual episodes. Compare this to, say, Dallas
, which is also an important series to American television, and one hat most viewers were probably still aware of even before the current follow-up. Yet if you asked all but the most hard-core of viewers to recall certain episodes they'd likely run out of answers pretty soon after "A House Divided" (where J.R. is shot) and "Return to Camelot" (where Bobby shows up in the shower).
Even the bleaker episodes have what would today be perceived as sentimentality. The monsters on Elm Street episode today would be like Spielberg's War of the Worlds, about the tragic need to unleash our inner monster to survive the threat. Etc.
Do you mean "The Monsters are Due on Maple Street?" I think it's quite a reach to label such an episode sentimental. Moralizing, yes, but hardly sentimental. (Considering this is a forum devoted to Star Trek
, it stands to reason most of the posters here don't have a problem with television engaged with moralizing.)
If it's your point that contemporary film and television is far less sentimental, I don't think it's very useful to trot out Spielberg as an example. Even the darkest entries in his filmography are ripe with sentiment, including his lousy version of War of the Worlds
(in which Tom Cruise wins and his family survives...somehow, because a happy ending must be reached).