Um, no. The spore drive isn't "rare and exorbitant," it's experimental. There are two ships. One went wonky, and the other one enjoys a wide latitude from the Admiralty. These crystals are apparently very hard to find, and once they're gone, they're gone, as we saw when Mudd used his.To say "let's use these extremely rare and unique crystals to blow up a few ships instead of using a handful of ships we can repair or rebuild to accomplish the same task" is to waste resources that could be best used elsewhere.
It doesn't change what I said, either. DS9 is considered dark and gritty, yet it had its own set of magic crystals. TOS, TAS, TNG, DS9, VOY, and ENT all had time travel, and all used methods that seemed almost conventional in their approach. I mean, hell, look at Star Trek: First Contact, one of the most popular Trek movies among the fandom. The Borg had temporal displacement technology. The BORG. You know, the species that hasn't met a people it's not willing to assimilate? Yet why isn't the galaxy full of Borg drones? VOY is the same. ENT had a whole Temporal Cold War going on in the latter seasons. I mean, really, only now it's an issue?