First, it must be understood that music possesses a morality - depending on what impact the music has determines whether it is moral or immoral. We are talking here about music itself - not just the lyrics. Proper music is designed to draw one's spirit into a condition of conformity to God. It is done through a proper balance of melody, harmony, and rhythm. When the melody of a music prevails, being supported by harmony and finally rhythm, it is healthy, moral music. However, when rhythm dominates the music and the melody or harmony is used to support it, it's impact becomes sensual and improper. This is what commonly characterizes "rock" music (together with the emphasis on the 2nd & 4th beats).
Regarding they enjoyment issue - I cannot deny that music - even inappropriate music - is fun. However, the standard that God-fearing people must use to make decisions about what they will and will not do cannot be the degree of pleasure we gain from that activity. For instance - fornication, drug use, pornography, drinking, etc... can all bring a certain level of pleasure to those indulging in them. However, the fact that one can enjoy doing these activities does not make them right. Likewise, simply because I enjoy a certain kind of music does not legitimize that music. I must deny at times, what I like in favor of what is good for me - cp. Galatians 5:17.
There is much to address on this issue - too much to get into here. But this is a thumbnail sketch of the philosophy of music that we embrace at ByronBible.