I don't expect average user to read an entire dependency tree. However, apt and aptitude does a relatively good job of explaining their actions' reasons.

Let me rephrase:

    1. Installation of recommended packages is a good default for the average user, because it provides functionality they expect.
    2. If the user is not happy with what's happening, changing defaults are not hard.

IOW, if you don't like how your system behaves, read the documents. Otherwise, I argue, current defaults is good for the benefit of the newcomer and average Linux user. If you are at a point where you are caring which package is doing what, you're leaving "average user / beginner" realm.

In the case of StarDict, as I noted elsewhere, I think the developer's answer is fishy, or ill-informed at least.