Well I'm glad you can acknowledge that it is not a good system. An even bigger problem than the system itself, is the amount of people who actually think it's brilliant.
And you are right, simply put: leveling is not fun right now. Some enjoy the grind, but many do not. It would be most beneficial for this game to have a decent climb of content leading to 50. Things like a few more low level dungeons like Toto-rak or even Shposhae with some repeatable group quests tied in. Hamlet defence battles could also provide some more leveling opportunities if they stagger the level ranges for various hamlet locations. There just needs to be some degree of option in order to break the monotony. Once this has been accomplished there is no need for a PL system.
As for level sync. Some people really seem to misunderstand the concept of this system. First, I will say that I was NOT a fan of this system in XI. With "skill levels" it produced seriously gimped players once they finally decided to start partying with people at their actual level. It also produced players who did not know how to play their role in a proper party setup.
These are risks you will always run with this type of system. As many have said above, people will always look for the quickest and most efficient method of progression. And once they find it, it will undoubtedly become one of the most popular methods. However, saying that no other methods will exist after that is a huge exaggeration.
But there are way to help prevent this from happening, certain limitations could be put into place on the gains from level syncing, limitations on range of levels that can be synced down to, etc. The point of the system is to allow players to play together, regardless of their level range. The concept is a good one, it can really help foster population growth in the game by allowing people to interact more with the new players coming to the game. Like any other system, there will always be those who over-use or miss-use the system, but it does not always negate the initial benefits of the system.