Wait ...
What is so extra ordinary about them?
Yes, they are not comonly met in Faerun ... but so are Githyanki. O_o
I hope I have interpreted your post correctly. If so, I would answer that it's their backstories which are so remarkable and the fact that they are all Level 1. Some have started that the explanation for them being Level 1 characters is that their 'powers' were removed by the tadpole, which to my mind is an awfully trite plot line. If for example only one of the companions had an exceptional backstory amongst all the other companions, then it might not be such a stretch but when all of them do (minus Lae'zel, whose only exception is that a Githyanki be a rare sight in Faerun?), it feels like a party of super heroes. I mean, come on, a vampire and a werewolf in the same party? When everything is special, then nothing really is anymore.
