Or the Federation just did the math and decided that the integrity of the texture of the universe wasn't worth protecting.
It would take millennia for any harm to be done outside the Hekaras Corridor, after all. And one should assume that there had been warp travel at higher than W5 for the past billions of years already - meaning the universe heals itself somehow.
Asimov's Foundation, Brin's Startide Rising and other works make fun of civilizations that explore the universe exclusively by going to the library. But it's actually even more ridiculous that the Federation doesn't do that. Wherever Kirk or Picard goes, somebody assuredly has gone there before! Whatever Starfleet discovers, it has been known to somebody else already, has been somebody else's problem, and either has been solved or has been the death of that somebody in a manner that might well be documented.
Yes, yes, there apparently are "great purges" where major civilizations die and become mere myth and legend, and lots of knowledge is lost, apparently because they take all the neighbors down with them. But that nobody would have studied this warp pothole problem before and lived to tell the story...
Timo Saloniemi