I've come to realize more and more lately that I use the same area of the fretboard quite a bit. Its just that the riffs I write there are soooo good, and really have the feel/sound that I expresses what I want the most. I'm able to write other riffs that are good, don't get me wrong. Its just that the only riffs that I really feel are in the same area with the same scale and sometimes even based on the same progression. And I tell myself it doesn't matter. Like look at blues. Blues guitarists are masters at this. But it would be cool if I were able to write something with completely different theory that has the same amount of feeling as my usual stuff. But I have yet to discover it.

So I'm not really asking how to branch out and learn the rest of my theory better, I'm just asking how you guys feel about this, because I'm sure I'm not the only one. Do you force yourself to write outside of the scales or chords that you've mastered, even though the results aren't up to par?
We're only strays.
I try to find idiosyncratic licks in each scale, like a Lydian lick, or a Phrygian riff. Try to find licks that are undoubtably one scale, like a country Mixolydian lick or a neoclassical harmonic minor riff.
It happens to me as well. It's actually one of the reasons I dislike dropped c and d so much because it seems like whenever I'm in that tuning, it always has to revolve around powerchords. I try to constantly remind myself not to box myself in a certain area so I try to pick certain places of the neck and work from there. Not exactly theory, but keeps things different.
try choosing an outlandish sounding chord like Esus (with the extra 2nd fret on G) or that D7 chord with the C on C#, base it around those euphoric chords and ur sure to come up with a very different sounding progression unattached to typical theory and common progressions... btw i play blues
A good band will transpose its guitar parts to suit the singer so I wouldn't worry about it anyway.
People writing songs that voices never shared
No one dared
Disturb the Sound of Silence