It doesn't make any sense to me:
If it's an attempt to bar low levels from farming high level resources or treasure boxes, it fails: you can just land on Correllia or Illum or Voss or Belsavis without issue and stand to gain better resources. If it's to prevent lowbies from navigating on their own in higher levels, the drastically increased range you draw enemies from suffices (I swear I've pulled mobs off cliffs for a chance to shoot me ) If it's to keep lowbies from taking high-end quests, well, the NPC won't talk to you anyways (c.f. core problem regarding inoculation) so it's redundant. If it's because there is something super special about Quesh...I must have missed it. It's an ugly rock only a drug-addled Hutt would enjoy.
The only thing it has so far served to do is prevent one guild member from joining us on a world-boss killing tour for that one planet, and block another from continuing their class quests until they gained sufficient levels.
For something that seems to serve no purpose other than add flavour to the planet (reinforcing 'Quesh atmosphere is bad umkay'), it feels rather harsh to block people from access based on level. I'm a Lord of the Sith and yet can't get some grunt to give me a needle? PIF!
I'd favour just lowering the npc's quest to level 1 and gives no real exp: keeps the effect without the side-effect. Likely be same issue with 'cold weather gear' for Hoth. Or tie it into story: your reason for going to Quesh is your storyline, so have that be your 'right of access', part of the class quest.
Of course I'm biased here: I want a level 25 Darth