Thats a nice video of Les's.
Firstly,
The wants of a classical guitar and a flamenco guitar are very different according to the music repertoire.
Flamenco guitars need a quick attack with immediate decay (NO sustain)-All the sound gets mushy if all those super quick hand techniques are played on a guitar without immediate decay (no sustain).
Classical guitars want good sustain, tone etc for obvious reasons.
Secondly,
the more a top is rigidly anchored at it's the edges (and also the stiffer the sides), the less energy is lost from the top through vibrations being absorbed into wobbly sides. Said again, The stiffer the sides, the more the top can act like a drum head without loss of energy.
A flamenco guitar wants floppy sides and kerfing. (hence they use a cardboard like, energy absorbing wood like cyress to make em.)
Thirdly,
Be wary of attributing a great sound to traditional methods like dovetails, hide glue etc. TO do so is to disregard the decades of thinking that luthier put into fine tuning their building and voicing of tops.
Ie-its like saying the amazing tone of Stradivarius is due to the varnish- i call total and utter BS. (PS- Strad used nails/bolts to help fix his necks on...)
Individual kerfing segments (tentellones) i think are somewhat a sign of the times (of old) and its building methods.
1- Individual pieces are easier to make and fit with the method a traditional classical guitar is built (top down etc).
2- I would not attribute a better or worse sound to tentellones or kerfing or solid linings.
On another note, I line my lower tranny brace up with my upper back brace and join them with a side splint. Don't know if it contributes to anything, but it looks nice.