First of all, players with early access have been playing the game for over 5 weeks. Getting to level 50 in that amount of time is no stretch of the imagination for any player, especially in a game that gives exp rewards for nearly everything you do.
Regardless, this isn't an issue about how fast one can level. The fact of the matter is an MMO is designed for its longevity and in a matter of months scores of players will reach the level cap just as in any other game. Players that are level 50 are the ones that have had access to all the content. We are simply trying to spread the knowledge that we have learned after many (enjoyable!) hours of gaming. And that knowledge is that end game TOR needs drastic improvements.
And to the argument that one should just re roll another character, for me, a big part of MMO's in the past has been the connection with your character. Designing a game around a repeated grind in order to see hear different voice overs with different characters may appeal to some, but I suspect most MMO players feel the way I do, and want to make one character as powerful as possible and hang with my powerful Jedi / Sith buddies who have set out to be as equally as powerful, if not more!
Anyways, I agree with everything said by the OP and in addition could go on for paragraphs about how PVP is dead in this game.