You are confused, because you can get up to level 50 for free, doesnt make the game entirely FTP... unless you like to level up alts all the time, which is not what mmo players really looking for.
FTP is there to make you subscribe or buy cartel items.
you can buy all the stuff you are missing by being FTP in the cartel shop, in that since its just like any other FTPMMO except you cant buy gear that is more powerful than what you can loot. and like i said above this is a free to play mmo with the option to subscribe to get the extras "for free"
but i am confused by what you ment about that you can level up to 50 for free but it dont make the game entirely FTP... also the bit about liking to level up alts all the time... i think im missing your point there kuz most people i know that play mmos have tuns of alt on multiple servers that they like to level up..