Regarding the OP's question: I really don't see how it has to be exclusively one or the other. There is an inherent drama to exploring strange new worlds that Star Trek has barely ever tapped. Think about "First Contact" (the episode), "Who Watches The Watchers?," "Move Along Home," "Allegience," "Justice"... While the quality of these stories varies from a real-world perspective, and while the Prime Directive violations mean that they are less palatable exploration experiences in-universe, they offer a taste of the potential for exploration stories to be highly dramatic and meaningful.
, you assume that visiting one planet in one novel and then visiting another in the next demands
a reset button. Narratively, there's no reason for that to be the case; it was only so because of the nature of television at the time. The novels are under no such constraint.
For example, there was no reset button at the end of "Skin of Evil," "Yesterday's Enterprise" notwithstanding. ("Skin of Evil" works as a story, regardless of Crosby's subsequent desire to return to the show.) There was no reset button after Wildfire
. You can still tell compelling long-term narratives within the episodic framework.
So yeah. I really don't see why it has to be either-or.