When I run into the average guitar player of genres such as indie, punk, etc, they are in the mind set that knowing keys, scales and other basic guitar knowledge restricts your creativity. In my opinion, they greatly expand your creativity.
When you know how to use keys and what not, you can think of exactly the way you want a song to sound, and make it. You actually invision your song, and the create it. Where as if you don't really have a knowledge of guitar, you basically just play until you hear something cool. I can't consider that art, because there is no vision in that. The lyrics are the last resort for any art if you use that strategy. Using keys opens you up to using awesome layers, more interesting leads and song structures, and tons of different genres of music.
I'm by no means saying that if you play out of key you're not a good player, because I often will modify a key, such as throwing a B into the key of F, as it can give very interesting sounds.
Chord spelling is to me a very important part of song writing, and you can't use chord spelling unless you know how to use keys, and harmonizing notes.
I don't see anything too creative in the song structure of random power chords in 4/4, yet the people who write songs like that are most often the kind who claim that keys are restricting their creativity.
Your thoughts please.
