It's common courtesy to be honest, not a desire to have things perfect. Though, I have to point out that it's actually the desire to have imperfection on the site that's the main motive for having slower FTL times (where, in a 'long' trip between Yamatai and Jiyuu, the time is still only 4 days). After all, what's more perfect than a nation that'll always be there to save the day within a few hours at least, and a single day at most? Moving on though. Yes, we can get some dirt and muck here and there, but it's considered pretty bad form to just drag them through the stuff without permission. I'd feel bad if someone did that to my faction, and I would think you'd feel the same regarding one you're attached to.
The Fridge Logic, or hindsight, to a situation or circumstance manufactured to get around the limitations of having fast FTL travel can also look very damning. Much like a movie you suddenly realize has a bunch of plot holes once you get home and are rummaging through the fridge in thought, hence the name. Plus...some factions could use a break from looking incompetent to be honest. Yamatai for an example, has such an incredible - as in, lacking credibility - track record, it's amazing all their neighbors haven't simply combined arms against it. Yes, we'll definitely get each other's toys dirty, but let's say it's my own faction that I'm having not come to the rescue as a GM. Yeah, I'll get it dirty too, but not to the point it looks utterly damning, or with repeat frequency.
My argument against having a fast FTL also includes the fact that it's always easier to reinforce, help or save people as a GM than it is to create the trouble to begin with. There's simply more tools on hand for it. With that in mind, why not make it easier for a plot's story to happen? Resolving it, OOC wise, is the fun part after all.