It just doesn't make a ton of sense to me in softball when you don't have fences on many fields. Defense can save (or cost) you on artificial turf fields. Or in the majors a sinkerball pitcher might get shelled but not let up a lot of HR. I'm not a pitching coach, but to me it means nothing.
That is typically how statistics work. Find the statistics that explain what you are looking for and go from there. I have not used FIP in the past, but I can see some situations when it could be useful. Let's say you have similar pitchers. One plays for a team with a strong defense, the other for a team with a weak defense. Obviously the ERAs will vary because of the number of errors, but the team with the better defense may also have fielders with better range. FIP can help filter out some of those items to allow better comparisons pitcher to pitcher. All depends what you are looking for...