Skill challenges do for noncombat what regular combat rules do for combat. Combat, in crude mechanical terms, can be viewed as a series of die rolls. The target numbers vary somewhat, but are set within a narrow band depending on the difficulty of the encounter. Each die roll gives a success or failure, with a certain effect following each result. Each character, depending on their build (class, race, feats, etc.) have a greater or lesser chance of being 'good' at a particular encounter. Player actions (tactics?) have a significant effect on the outcome. Each character needs to make a contribution, or the effort is doomed. There's definite consequnces for success or failure.
Sure, the specific numbers (and especially numbers of die rolls needed) is very different, but conceptually the process is similar. In fact, it's helped me by acting as something of a reminder to cover all these aspects when designing a skill challenge.
From where I stand, what skill challenges don't have is three things: one, visuals - map and miniatures. Instead, it's all narrative and description. There's no toys or props to play with, which makes it less immediately and viscerally accessible. Two, long lists of detailed powers and feats. Yes, there are some utility powers, but they are largely secondary to the focus of the game material. Like maps & minis, it makes challenges less instantly attractive; when most people look at a class, they don't see "ooh, this guy would rock at diplomacy" - they say "ooh, this guy can do massive damage." Three, consequences. To fail in combat is seriously punishing, if it isn't a TPK which ends the adventure. Whether or not challenges should be equally crucial can be discussed, but from what I've seen, many published challenges are merely annoying if the party fails. Thus they invite neglect from goal-driven (not to say power) gamers.
The skill challenge motif goes a long way toward making noncombat action interesting, by applying some parallel procedures. There's always been so much focus on combat, it's nice to see the work presented in this area. (For the record, I'm not saying the focus should change entirely to noncombat; but it's nice to have the structure developing.)
Just sayin'.