Since my initial post, I've done a few more pictures and photoshoots and have come to a different conclusion than my original. During my last photoshoot, I stuck to the DA21, DA35 and DA70 Ltd. However, when I was using the DA70 Ltd, I found I was "limited" by the single focal length. Let me explain.
There were times that I had an angle on a shot but could not take it b/c I bumped into an object that was behind me as I tried to "widen" a photo using the DA70 Ltd. I ended up moving around in different directions to finally crop the picture the way I liked it, but this resulted in all the elements moving and making for a different photo altogether (DA35mm = too wide, and again... totally different picture). Furthermore, there were times that 70mm was too tight and cropped, but I didn't want to move back because I had a certain angle that I wanted (and I was standing on stairs). I ended up with photos slightly more cropped than I wanted, different composition, etc.
After all this, I went back home and looked at my DA*50-135 and I realized how very useful it would've been in those particular situations. This is not to say that the DA70 is not a great lens... It IS! But at times when I would've loved a 65mm or an 85mm or 125mm look (and I don't want to move to crop), this zoom would've come in handy. And probably a lot easier than carrying 20 different prime lenses.
So this has me re-thinking everything. I think primes can definitely get you into the mindset to compose your pictures before shooting. I'm actually very glad I've stuck exclusively to primes for the past 2 months or so because it taught me composition through restriction. It forced me to 'think and move' to create the picture instead of just zooming.
And I think that's what I needed to learn: better composition! Regardless of prime or zoom, I think making a photo comes down to (1) creatively composing a picture and then (2) using our techniques (and lenses) to create it. I'm still learning, but I think primes have helped teach me on both those things!
I'm still planning to use primes a lot, but now I'll be bringing the DA*50-135 zoom along for the ride