Well, I don't see a reason to change anything here. Leina's, Melora's, Dar's, Shar-Teel's, Taffic's quests - all are optional, as well as all quests in Chapters 2-3. There is a walkthrough by Richard, and I hope in future he will update it with new quests.
Also it's possible to ask this question at the forum boards. When you play such a game like BG for the first time you are not supposed to know without walkthrough that there are many optional quests, and I'm pretty sure that many novices including myself when playing BG-BG2 for the first time have missed those quests. Anyway, in my opinion it's not worthwhile to touch well-working quests for the sake of some minor and questionable scenario improvements. By the way, after BG1 + NeJ2, my capital is approaching 1 million. Adventuring is really a good buisness.