A major complaint I have had about the d20 core rules is that the classes are largely boring and weak tea after five or six levels. For example, why would you ever want to continue as a pure barbarian after the first seven levels? Assuming you had the stomach to make it that far.
The reason for this is that Wizards of the Coast wants you to need to use prestige classes, thereby creating a demand that splatbooks fill. Although prestige classes (and feats) are obviously a selling point and half the point of splatbooks, it had not occurred to me that marketing concerns might have dictated the nuts and bolts of the basic classes.
The basic classes were intentionally made boring to generate sales for WOTC. Amazing!