I politely disagree. In my opinion, most of the mods is made because of either some creative urge or of the urge to correct game's faults, or both.
I, for example, wasn't much entertained by the vanilla game and was gradually more and more irritated by endless hack'n'slash and by the time I reached Sendai's Enclave I gave up on the game entirely.
Years later, I 've given the game second chance, this time with a bunch of mods installed, and it was much better experience.
For example, whole expansion is, in Minsc's words, "less talk, more fight". With some mod NPCs, especially Longer Road, this, for me unpleasant, disbalance was gone.
In original BG2, romances were more annoying than fun, and dialogue choices were usually simplified to two basic responses. Some mod romances redeem this with more natural and complex flow.
Even in SoA, there is emphasis on combat which I wasn't much fond of, but after installing some more talkative NPCs, things started to feel more balanced. Of course, there is quite a lot of talking in the original game, but a lot of dialogues isn't particularly interesting.
Also, after chapter 2 which I consider to be highlight of the vanilla BG2, you are railroaded through the main story by going from one plot point to another with a vast amount of fighting inbetween. So, for example in chapter 5, I was glad of having Xan with my party, because it offered me a possibility to stop between fights and engage in some, usually quite funny, conversation.
Imoen wasn't originally meant to be in your party in later chapters, so her character is extremely underdeveloped in SoA, again, banter mod and some mod NPCs gave her something to talk about.
And there's more things - romances are bugged, paperdolls are artistically poor, inventrory juggling detracts from actual playing, "you must gather your party" breaks the immersion and so on, all of this is rectified by mods I've listed earlier.
Of course, combat in Baldur's Gate can be actually very fun and engaging, given its complexity, but it needs some time to be appreciated. Carefully chosen mods can give a first timer some space for breathe in between them, help to decrease repetitiveness,also enhance and deepen those roleplaying non-combat aspects, thus help to "retain balance". All of that is very subjective, that's for sure, but it worked for me.
All in all, at the point I installed some carefully selected mods for it, Baldur's Gate started to be much more interesting experience for me.
