Much excitement is derived from the Jersey Shore's ghetto-style assault on professional culture in the US. For starters, professionalism is a mandatory form of socialization insofar as anyone hopes to meaningfully "succeed" in US society; it affords the only kind of social status and power made available to the working classes: a respectably elevated position within the social hierarchy; or, power over others.
Many people resent this whether they are professionals or not. From a very young age we are taught what we need to do if we want to have any kind of respectable life, and by and large this entails conforming not to our own standards of right and wrong but to somebody else's. Somebody else, after all, has in their possession what we need to live respectably, and we have to get this through them. We do not learn that we can be respectable by "just being ourselves" in a comprehensive way.
The appeal of the Jersey Shore comes precisely from the notion that the cast members are "just being themselves" in spite of the fact that this often exceeds the scope set by the idealized norms of professionalization. No one in their right mind is supposed to "just be themselves" if this is likely to antagonize a potential employer. US audiences understand this implicitly, owing to the experience of class in their lives: if they behaved like someone on the Jersey Shore, or merely like "themselves," they could lose their social standing altogether. Any population so dependent on external sources of legitimation is subsequently enthralled by apparent examples of individuals who don't give a damn.