You have a point that some people don't have the talent to decompose objects from their mind'e eye into basic shapes. I would argue that some forms of drawing are based more on practical skill sets, which can be learned, as opposed to the ability to detect the pitch released from a musical instrument. (I make that claim as a guitarist myself)

Trying to improve your drawing ability is worth the time and effort spent. I have been working on improving my artistic lens for the past month. Am I yet at the skill level I want to be? No. Have I sacrificed a lot of time? No.

I sit down once a day whenever I can find 10 minutes, set a timer, and sketch whatever comes to mind. On busy days I skip this practice, but always make it up in the following days.

You can see the progress in this imgur album: http://imgur.com/a/GTF6w#0 . These are by no means exact representations of the image in my mind at the time. On the other hand, they are quickly getting closer to my imagination everyday.

For a practical book on the topic of drawing, I recommend http://www.amazon.com/The-Drawing-Right-Side-Brain/dp/087477... .Reading that book helped me gain a lot more confidence and understand a lot of the science behind drawing ability.

I also have a large amount of bookmarks on improving your pixel art skill set. If those would be of interest then I am happy to share those links.