Nope. I got all of your point. Learn to ride properly with the right instruction and all will be well. You will develop proper skills over time. That is the ideal. I get it. It's you that missed my point.
My point is that although in a perfect world, you would get this proper instruction, learn, practice "the right way", get it, and become the next Valentino Rossi, in reality this is usually not the case. Not everyone has a fast learning curve, but just because you don't learn fast, it doesn't mean you shouldn't ride. Those with a slower learning curve plus a bike they're not comfortable with may drop their bike several times more in the first month or two of riding than someone who learns fast. With or without instruction (realistically an instructor can't be with you on every single ride you do). Any of those drops could lead to injury.
If having a lowered bike reduces their drop numbers in half, their risk of injury is also halved. That's a good thing. IMO it's
safer to learn on a bike that you're comfortable with, then move up, than to just jump into something you're not comfortable with, even with instruction. Yes, like you said, ideally you would learn on that 125cc. Therefore, if on impulse, your R3 ends up as your first bike, the next best thing would be to learn on a lowered R3 (if you feel you need it lowered). The 3rd best would then be to suck it up, and learn to ride it at stock height.
Sure, proper instruction and practice can get this behind the OP, but while he's in the process of "getting it behind him", his risk of injury is simply higher than if he just lowered the bike first, then brought it back to stock height after he's comfortable riding (or just say **** it and leave it lowered forever. If that's what he wants, who cares.)
You can disagree, but you missed most if the point. Proper instruction and practice can get this behind the OP, but I'm guessing by the tone of the posts they don't want to continue building skills and putting in the work.
Starting on a small play bike, like a TTr125 is about the best way to learn, but most new street riders impulse buy and don't know what they are getting into. A few weekends in a sandy field with a teacher and a mini thumper pays big dividends.