There's also a matter of context. Trek did this :
When it's contemporaries were doing this :
And even big budget movies were doing this :
Hell, only a decade or so before the average science fiction spaceship looked like
this :
Or this :
The Constitution class was an absolute revolution in science fiction. Compared to the kinds of things that had gone before it was mindblowing original and vastly superior. And even now, over 40 years later, virtually every single design you see in Trek is some kind of variation on or refinement of the Connie.
And personally, I don't think there has ever been another sci fi spaceship design that feels as genuine and real as the Star Trek ones do.
Give a man a fire, and you keep him warm for a day. SET a man on fire, and you will keep him warm for the rest of his life...