At times The Twilight Zone
could be quite sentimental, but that overlooks a great deal of episodes with a much bleaker worldview.
Like all television, the series was a product of its time. It is, of course, being frequently broadcast now, but if new episodes were being produced they would be quite different (witness the differences between the original series and the revivals that were produced in the mid-80s and early-2000s). The original series really is quite good and appreciation of it hardly comes down to simple nostalgia.