It's tough because it's a relatively precise movement that comes in most handy in panic situations. I like MoM's description,
because, though I'm not as experienced, this is what I'm striving for and starting to feel. Once you get used to it, you'll naturally treat the throttle as the analog input it is (as opposed to the morse-code On-OFF) at all times, and the roll-on/roll-off will be replaced by smooth, semiconscious modulation. Once you hit this point, I dare say you'll be better off than most riders.
This is partly why it is so imperative that riders be relaxed on the bars when they ride. If you're bearing down with all of your weight on that right clip-on then it takes longer for your brain to convert the cognition to action because you first have to tell your hand to relax. OR youre just working against your own weight to delicately open the throttle.
When I was new to riding I used to practice while riding up and down the freeway to work. I would start by holding the throttle at a consistent, specific speed, then I would crack it by mere milimeters and interpret the feel of the transfer until I could understand exactly how and when the bike registers the input.
Also; what you'll find is that some bikes require more or less finesse when working the throttle-brake combo. This can be due to a number of reasons - power configurations (amount of cylinders, bottom end/top end power, 2 stroke vs 4 stroke, displacement, etc.); or mechanical logistics, modifications, etc.
When I rode my buddy's 848 for a few months, I really had to get to know THAT bike because the throttle response was much different than that on any of my bikes. Add to it the fact that it was re-geared and modified and it changed even more.
On some bikes a dip, or delay, in a certain RPM range is pretty typical (a design quirk if you will) but in cases like that it can effect the input that you give even if you do it flawlessly. On my 636 (streetbike) there is a lot of wear and tear that has led to delays in throttle response, and some inconsistent power that could be indicative of crap in the system, or a faulty mechanism or sensor. If I hadn't taken it on the ride the other day, I probably wouldn't have noticed. So now I get to start addressing that when I do the rest of her winter restoration.
It's important to know where your bike's quirks are as well. In fact, becoming more proficient in the principles of throttle control can actually make you more privy to mechanical problems that the bike may have as well. If, for instance you know that you are rolling on smoothly, but you feel subtle reactions where once there weren't any, then you might be headed for other issues down the road.
Understanding the relevance and application of all of it will, indeed, make you a better rider than those folks who just fly by the seat of their pants. When you look at the operation of a motorcycle (sportbikes particularly) as a craft, then you will stand to gain a lot more out of it than the guy who just gets on, winds it up, and throws it into some corners because there is SO much to understand about them.
You may even stand to live longer as well.