Good tone is whatever gets you to where you want to be, and any control that gets you there is fair game, but I'm sorry to disagree on the function of the Definition control. I don't believe it is a guitar compensation tool. I use it as a final fine tuning for the amp center frequency, and rarely have to push it very far to find the sweet spot. And sometimes in A/B ear checks the original setting from the profiler sounds better than what my alteration sounds like. You have to be honest with yourself, as what you think sounds better in the moment needs to be checked with a verity of tests. I look for clarity of all notes and chords played, and go through many complex chords and lead ranges on the fretboard with all my guitars looking for total balance, but the main tone controls are the first place to start. Definition is the final tweak.
Maybe my goal is different, as I want amp tone that works with any guitar that I plug into it. If going from a Les Paul to a Tele hurts my ears, than I screwed up by pushing the tones too far in one direction. And yes, I want "amp in a room" sound, as I do know what an amp sounds like in a room, and also know the perfect listening position from the cabinet. That is one of the strengths of the Kemper...consistency no matter where you stand. No doubt mics alter that finished product, but you can actually use that to get a "better amp in a room" finished product. That is why choosing the right cabinet matters so much. I look for balance there too, and rule out anything that stands out too much. In the end I can sound very "live" and plug any guitar in with total satisfaction. Mission accomplished!
No one method is better than any other, as tone is subjective anyway. As long as you are happy with the final product, you win. I just treat the KPA like my real amps, and want both to sound the same and respond to all my guitars the same way. The good news is I can get an even better final product out of the Kemper because of all the fine tuning controls. Those go beyond what you can do with a real amp and cabinet.