Abstraction is best defined for me as similar to generalisation in many ways - it's the act of taking something and removing specifics, generalising it to the point that it isn't really "about" something, but is more likely to represent a concept of a feeling than any specific image.
One of my favourite artists would probably be considered Abstract: Kandinsky is more known for his use of Colour than anything. He had colour/tone Synaesthesia, which for me adds another dimension to his paintings. Simply, though, I just adore the colours he uses:
Regarding the initial topic, I would imagine that it has been extensively argued that technical ability isn't everything. It certainly isn't for me. Music is much more about the soul of the piece than the sheer technical skill of the musicians. While listening to technically skilled musicians can be fantastic, unless the music has that all important depth of soul, it will never truly grip me. Similarly bad playing is just annoying, but something simple but thoughtful and emotionally strong can hit you much harder than the fastest guitar shredding in the world.