A person's interpretation of music is what matters to you alone.
To say rap isn't music is pure ignorance because then I could consider most of the rubbish I hear today none music, music where lines are stolen from other popular artists or bands, or where the vocals and intrumentals are recycled, or in pop where the same verse is repeated over and over and over like as if it is some kind of new trend. Even the quality of some rock has gone down.
I believe there is crap rap, where females are inaccuratly represented and money is the topic of conversation, but there is also rap where the artist has taken an incredible amount of time considering what they want to put into thier lyrics, which could be hours or even days spent at a library. Kanye West for an example was like that, Nas was also like that, if anything, those two artist spent more time considering the actual meaning of literature than many artists today in ANY genre of music. There was more time spent thinking of the meaning of what they were rapping about then a lot of rock, country, pop and half the nonsense people consider to be music.
The very premise that you could say thier rap isn't music but the likes of Rihanna, Katy Perry and several others either singing the same verse or singing about love and love problems (which is the most popular music theme since music was invented) is almost insulting.
The Roots for example have stepped beyond the boundaries and combined rap and hip hop elemnts with rock, thus appealing to both genres, but you will find they are much less popular or well known because they actually spend time making thier music.
Black Eyed Peas used to make very well thought out music, I absolutly loved it, now they make club nonsense that people today consider to be 'music'.
So when you talk about music, just what standards are you setting and in what way has Rap not fit into those standards other then a melody, which means nothing because people are attacted to different forms of melodies, if thats the case then most metal isn't music either because the melodies rarely attract me, if anything, they irritate my ears, but yet, I appreciate it as music and respect those who love it.