Someone else pointed out what we know — mass culture is a product disguised as individual self-expression:

In the sphere of luxury production, to which popular music belongs and in which no necessities of life are immediately involved, while, at the same time, the residues of individualism are most alive there in the form of ideological categories such as taste and free choice, it is imperative to hide standardization. The “backwardness” of musical mass production, the fact that it is still on a handicraft level and not literally an industrial one, conforms perfectly to that necessity which is essential from the viewpoint of cultural big business. If the individual handicraft elements of popular music were abolished altogether, a synthetic means of hiding standardization would have to be evolved. Its elements are even now in existence.

The necessary correlate of musical standardization is pseudo-individualization. By pseudo-individualization we mean endowing cultural mass production with the halo of free choice or open market on the basis of standardization itself. Standardization of song hits keeps the customers in line by doing their listening for them, as it were. Pseudo-individualization, for its part, keeps them in line by making them forget that what they listen to is already listened to for them, or “pre-digested”.

The most drastic example of standardization of presumably individualized features is to be found in so-called improvisations. Even though jazz musicians still improvise in practice, their improvisations have become so “normalized” as to enable a whole terminology to be developed to express the standard devices of individualization: a terminology which in turn is ballyhooed by jazz publicity agents to foster the myth of pioneer artisanship and at the same time flatter the fans by apparently allowing them to peep behind the curtain and get the inside story. This pseudo-individualization is prescribed by the standardization of the framework. The latter is so rigid that the freedom it allows for any sort of improvisation is severely delimited. Improvisations — passages where spontaneous action of individuals is permitted (“Swing it boys”) — are confined within the walls of the harmonic and metric scheme. In a great many cases, such as the “break” of pre-swing jazz, the musical function of the improvised detail is determined completely by the scheme: the break can be nothing other than a disguised cadence. Here, very few possibilities for actual improvisation remain, due to the necessity of merely melodically circumscribing the same underlying harmonic functions. Since these possibilities were very quickly exhausted, stereotyping of improvisatory details speedily occurred. Thus, standardization of the norm enhances in a purely technical way standardization of its own deviation — pseudo-individualization. – Theodor Adorno, On Popular Music

This doubly applies to nu-metal. The whole essay is worth reading.