I have to say that I think your post is an unfair characterization of how BG2 was designed. By "Chapter 2" you seem to mean "all the possible quests you can access starting in Chapter 2". I mean, the game was clearly designed to have these sidequests and fights cleared in the process of your adventure -- in Chs. 2, 3 and 6. This might seem like semantics, but that's basically half the game. And while many players, myself included, do most of it in 2, the design there is obvious, with several high-level fights available if you want them, but plainly designed to be done ideally in Ch. 6.
So, I think it's incorrect to say that Ch. 2 is "well developed" compared to the other ones, your arguments relies on exclusively assigning all the content to one Chapter.
I do think the designer's original point is sound, in that you can fill up your journal with initial quest notes way too fast. But with the strongholds and the open path to gold goal, I don't see any other way this would work.
