(just Corellia and Ilum are dead for some reason
You can blame all the ridiculous accelerated leveling this game has and that's even without 2xp weekends.
Everyone is max-leveled by the time they're done Belsavis even just doing class/planet missions. There's no incentive to go to either planet and actually do anything now cuz there's nobody there other than Datacrons and a few end-game missions.
If a veteran player wants to power-level using all the boosts possible, I can understand that, but it's the new players that are getting into the game that suffer the most cuz they level too fast, get to Corellia, and wonder where everyone is.
I think that's who it hurts, the new SWTOR player, they hear all the great things about class stories but then wonder why even bother when they are just smashing through levels, then it's just like every other MMO. So then you get all these noob players spamming to join guilds cuz they hear all about the guild XP bonus and then they speed to 55 and have no idea how to play their class.
I'd love to see Legacy restrictions on all forms of accelerated leveling, then you'd get just the players who have played the game "properly" at least once being allowed access to the XP perks, but that will never happen.