I fell sooo sad about someone who need to have multiple account to play a game, is worse than these people who do things to get attention.
Players who create multiple account don't do it to increase the dynamic of the game, have each of every class, to have a different point of view of oneself and the surroundings. A player with 10-15 different characters is just repeating himself on multiple clones, same characteristic, same ideals, same believe, hell. Is hard for many to separate two characters just imagine 10.... All i can do is feel pity for that kind of person.
I would take groups who plays together (called clan) over multiple account any time, even if they are strong, you can feel that they are different characters, their only downside is that they remain silent for most of the time.