It seems that people have been brainwashed by Pay-to-Play MMOs in that, for some reason, grinding to get to a high level is 'fun' for them.
Please. Don't confuse Guild Wars with all the other MMOs that purposely impede your progress with grinding in other to keep you playing a game longer. If you want that sort of game, well, there's dozens of options for you to go for. If you want some extra grinding, feel free to play some of the korean-made games.
As for GW Factions, the purpose of the game isn't to use your extra high level to beat the monsters, but instead, to bring the focus on how you make your party. In other words, teamwork, as opposed to making GW just another 'my stats beats NPC's stats, so I win' type of game.
But hey, that's just my opinion... I enjoy the game as it is, I enjoyed how Factions focuses less on a grind-to-level-20 and instead focuses on skill (and by skill I mean, real-time decision making, on-the-fly adjustments to enemies and organizing your party's attack schemes).