Scales are important for a guitarist, just as learning good grammar is important to speaking properly.
If you are intent on "playing" guitar then learning the language of music is going to be inevitable.
From my own personal and teaching standpoint, guitar music should start with Chords. As opposed to notes. To me they are the most practical form of music as they are immediate. Consider chords to be words.
So like a child, you are taught "MUM", "DAD", "YES", "NO" - so you might learn the chords G, C and D. That may suffice you if all the conversations you will ever want to do on guitar is in the Key of G, eg. But soon you will want to know other things, like Em, Am and now the intensity and complexity of MORE KNOWLEDGE comes into play.
Well that's where SCALES comes in. They are the alphabet of the chords that you play. It can make a difference from a chord progression / accompaniement sounding like "GOOD MORNING" to "GOOD MORNING, HOW ARE YOU? I FEEL FINE!, ISN'T IT A GREAT DAY TODAY?"
Scales can set the tone. Knowledge of this alphabet allows you to add twiddles and trinkets to your rhythm work... that is, adding little fills based on your knowledge of scale shapes or forms or even better - true music theory where you know whether a particular note is a flat 3rd or diminished 5th and whether it is a Lydian or a Phrygian mode of a scale. All this KNOWLEDGE of SCALES allows you to set the mood and tone of your playing.
Now the connotation of scales is another thing entirely. In my mind, metal and hard rock styles have tinged the learning of scales slightly as SCALES often gets equated to SHRED. But that's not the case. Even styles like Blues and Jazz and Latin all have their tones and styles completely defined by the SCALES that are dominant in their music structure.
Last week, for example, I was explaining to one of my students the elusive difference of the MAJOR and MINOR scale change of a Blues progression. This was invaluable information to him - because it now explains what he can hear in records/songs. He knew there was something going on but he didn't have the vocabulary to explain it - which translates into better technique and conscious choice in what notes to play.
SCALES will lead to understanding; the ability to know and recall relationships between notes; this leads towards understanding the relationship between chords and how this sets an emotional mood; this leads towards understanding good composition and song writing; this leads towards good technique and more interesting rhythm work; this leads towards a roadmap for soloing and knowing various melodies to play over the right chords at the right time; this leads to complete mastery of the guitar.
LEARNING SCALES can do this for you. It's invaluable and will open up the guitar for you.
