Re: So why doesn't Spock save Vulcan?
Honestly, any episode where time travel apparently occurred within the same timeline could just as easily have been travel into an alternate but very similar timeline.
I disagree that the Defiant
being replaced as quickly as it was necessarily reduced the dramatic impact, especially given that anyone viewing the series will realize that it was constrained by certain practical matters.
It was the best of Trek, it was the worst of Trek...
"If I lean over, I leave myself open to wedgies, wet willies, or even the dreaded Rear Admiral!"