Ominous:
There are several different levels of analysing this situation. It comes from a creative standpoint, as well as a business standpoint. Looking at these two subjects can really open a further discussion regarding the stance of hip-hop music today.
Creativity
From personal experience, I do not believe that there aren't creative people out there willing to contribute to a revolution in the hip-hop scene. With the underground movement spreading, fueled by the internet and by a greater disgust of the mainstream, underground artists in hip-hop are clearly marking a niche territory. However, this is not the underlying problem to why hip-hop has not changed.
The problem is that when anything completely different is introduced to hip-hop audiences, and is truly distinctive, most of the time, that "sound" is not appreciated. Unless, of course, a big name artist, or major producer agrees to backing a song, which thereby relegates the mass public into believing that there is credibility to the new sound of the track. Noreaga did this to the Neptunes in 1999, and Timbaland was able to introduce his new sound in the mid-nineties via several big named artists who wanted something fresh from the previous "sounds" dominating the scene at that time.
Though some may argue, I've heard Timbaland's style years before he became popular, in the albums of a lot of UK Electronic Artists. For example, his avant-garde stutter programming (like on Missy Elliot's first album, and Jay-Z's "N*gga What?") were being done in Europe years before. His acid bass lines in Aaliyah's "Try Again" which was touted as revolutionary, is another such example of him borrowing from European electronic music. His Arabic sounds on Tweet's album, was taking a big part in clubs in Europe years before he ever used it.
Anyway, as Afriquedeluxe implied in his post on "Grindin' " produced by the Neptunes, there is a tendency for anything that is mass-marketed to give a producer instant credibility. The public is simply a herd in many instances.
So, to bring my point across, even if you do bring something fresh and new, many claim to say it's not "hip-hop," and the negative reinforcement will dissuade many people from being avant-garde and pushing forward. Ultimately, they get sucked in with the mass of producers all doing the same thing. The concept is to be creative and also strong-willed as to not let individuals dissuade you from doing the type of musical production you enjoy?
But what if you want to get paid???
Business
The need for profit and maximisation of cost and benefits has created a cash-strapped major label recording industry that has an want for the "hits." The specificity of certain music at certain times show many of these businesses the benefits of not shaking up the musical mainstream but catering to the public's needs at a specific moment. That is why many songs sound alike and have the same formula. This gives a greater probability for a company to have a return on their investment if a song is mainstream enough to guarantee some form of "hit" status. It is extremely costly to take risks in the entertainment industry, due to corporate pressure on return on a capital investment.
So, many producers who want to make money find themselves not catering to their wants in an avant-garde fashion, but will play by the rules and create songs that sound like others in order to get the bills paid because record companies want certain types of songs from these producers. Obviously I'm not talking about underground artists, but the mainstream. The business angles are a bit more complex than what I've laid out (if you want me to, and I have time, I can discuss that further.) There is an intense focus on market analysing and catering to a common denominator rather than exhibiting anything truly different and new. If it is different and new (from perception) it still follows a rule of catering to the common denominator: this is evident in 50 Cent's recent success. However, I remember 50 Cent when his name was "2Pac" and he rapped better, or when 50 Cent was a group called "N.W.A." and they had more thought provoking lyrics (in some instances) than 50 Cent has at the current time. 50 Cent's image and persona has been applied many times in the past, and his angry bad-boy image transcends into rock and other forms of music which were once considered as new and fresh as hip-hop is now.
There are many people all shooting for being the next Dre and Timbaland, or whoever can shake things up. Remember, there is only one Dre, one Tim, one Neptunes, and the times when they affected rap music are far between. Producers see the odds stacked against them, and will cater to creating a mainstream hit at the current moment, rather than changing the game. I can count the people who've changed rap music in the last decade on one hand. A lot of producers look at that and wonder if they can beat the odds. Usually, they can not.
Creativity and business are hard to compromise.
Sincerely,
God