Yep, CV routing is very useful. I used to just automate everything via MIDI when I was trying to emulate Autechre back in 2002. I would design all my drum sounds in Orangator (what a neat synth!), then I would put all the samples in Redrum and edit all my synth parameters in the piano roll. CV didn't make sense to me then. Now, I use it all the time. CV works in the same manner as automated MIDI, without having to mess around with drawing the curves (unless you want to).
One user posted the movement of clouds - an apt example. Free movement of sound (pitch, timbre, etc.) within a controlled environment. Very useful. CV is also excellent for making rigid (or "swung") sequences that sound different that what a keyboard player could bang out or finesse with their fingers. It's not the only way to do things, but it's a really handy way to do things, especially since the environment allows us to control more parameters than we have fingers for. Sometimes a simple riff is all a song needs, and sometimes an undulating robotic sex demon is what a track needs. Also, for sound design purposes, some of the features on some of the synths only have CV control to do fine shifting work. Imagine listening to a sound effect on loop that is one second long, and trying your damndest to shift the mod wheel "just right" every time, by hand. Whoooo! CV to the rescue.
Learn it, live it, love it!
The main thing to keep in mind is that many of us who use Reason are not keyboard players, nor traditionally trained in music composition. For some of us, we hear a sound, and want to create a different sort of music. Piano keyboards, notes, rests - they can also be realized with CV sequencers, and offer a physical/visual way to realize our imagined sound. We are all, to some extent, "musical". It's a matter of how one chooses to compose that makes music a fluctuating, living, breathing entity. Imagine if everybody did it the same way!
All hail CV as a venerable and useful music production tool.
On a side note, if anybody has been having issues understanding CV, sometimes (just like math, science, or language arts), the way the principles are being explained may be the cause for confusion or being overwhelmed. We may understand that someone is confused, but not what exactly is causing the confusion. Feel free to actually explain what is overwhelming about CV. Please, don't give up, find a different angle, I'm sure somebody else out there may have had a similar situation. Personally, I know a little about CV, but I still have a lot to learn, myself. Time and practice is needed to get a better understanding.