JarlFrank said:
BG1 just screams "generic pen and paper adventure that everyone has played at least once!" at you. It's just like all those cheap fantasy novels out there. Generic and without surprises.
I don't think there's anything boring about standard fantasy settings, particularly those that are as classical and standard as possible, such as Forgotten Realms. What is boring are uninventive deviations from the norm, such as altering some aspects of the standard races in an extremely uninspired manner. To say that standard fantasy is boring is like saying that a RL setting without fantastic elements would be boring because there won't be any setting-related surprises pulled out of the blue.
One of the interesting advantages of non-deviant fantasy settings is that they allow the usage of background knowledge. A primitive example would be not to inform the player of the weaknesses of a monster and let him derive satisfaction from knowing how to defeat it from an outside source (e.g., Monster Compendiums, mythology, other games, etc.) I'm quite certain that standard fantasy-specific realities could be used this way to compose complex quests. At the very least, various allusions could be employed to enhance the atmosphere and create a sense of the vastness of the world without actually showing it in its entirety.
Theoretically, a familiar setting would allow the player to switch his attention from the setting to the characters and situations, but that doesn't seem to work most of the time.
P.S. I would actually argue that BG1 is quite unique in the sense that it deals with low-level adventures. Even towards the end of the game the party is relatively weak and unassuming. I am quite sick of all those uber-spells, epic monsters, heaven and hell, et al. I wish there were more fantasy games that would let the player mingle with the peasants and townsfolk in the role of ordinary adventurers.