Thanks for the responses, many valid points. At this point I don't want to weigh in with my opinion. But I want to throw a couple of follow up questions into the equation.
Does it make a difference if a Hip Hop/Rap artists plays their own instruments?
For example this was the case of many of the alternative hip hop artists of the 90's, such as The Roots (who don't the meet the 25 year requirement yet)
Concerning lyrics what about those hip hop artists (which applies to a number of the Golden age of rap artists of the 80's) who actually did rap about real life political and social issues. Would they be more deserving than those who resort to constant profanity and sexism?
What if a Rap artist includes elements of rock into his sound and even has had a direct influence on rock artists should he be considered?
What if the artist gets a lot of modern rock radio play and maybe even had it's roots in hardcore punk (like 2012 inductees The Beastie Boys) does that make a difference?