That is completely debatable. In a game where an "endgame" does not exist, or rather has been marketed with no real "endgame", the usual rush to end level is not really desirable. For me, I never play "endgame" in MMOs, it is a huge treadmill, but that is another debate. What always concerns me is this "drive" to level up quickly to catch up with your friends. I am an explorer, preferring to explore every inch of a game world, sample all it's detail. It always means that I never really get to group with friends as they are always streaking ahead in MMOs. It is why I have always LOVED city of heroes, you are able to join your friends in higher level "dungeons" even from low level and have fun together and gain from it. I heard rumours of GW2 having sidekicking and it immediately peaked my interest as it would allow me to join up with friends.
"Endgame" designed MMOs have a gating of content, purely because they want to ensure people do not experience "content" too quickly as then those people have nothing to do. This is the biggest reason why these MMOs do not have a sidekicking system. I am hoping GW2 will give people lots to do and not gate people from content.