I just started playing last week as a F2P player. I'm not sure if I fully understand the gear system yet.
Take green gear as the base. Blue gear is better stats with a lower required level. Purple gear is better stats for the level, but with upgradable sockets that are already filled and require an authorization unlock. Orange gear is the same as purple gear, but has upgradeable slots that are empty and usable without an authorization unlock.
With the rate of planetary commendations from missions/drops and cost of socket items: why would anyone buy blue gear as a F2P player, or purple/blue gear as a non-F2P player?
I can understand going all out green/mission items if you are trying to make money off the storage boxes from the commendations. Otherwise, you can almost fully outfit your character with orange items when you complete Taris at ~25 if you also run flashpoints.