I don't fully understand how these various comments fit together.
Isn't weakening dragons "reducing the challenge"? In which case, you don't seem to have a problem with that.
But in any event, what counts as a challenge is mechanics-relative. In AD&D, for instance, a starting 1st level, fighter can expect to be hit by 1 in 4 or even fewer attacks (say, AC 3 vs THACO of 19 or 20, requiring a 16 or 17 to hit). In 4e the starting fighter is likely to have AC in the neighbourhood of 18 and be attacked by creatures with a +6 or more to hit, meaning that nearly half of the attacks made against him/her will hit. And the damage in AD&D is likely to be 1d6, whereas in 4e it will be more like 1d8+4.
The 5e maths are closer to 4e than AD&D: a starting AC of 16 or 18 (depending on shield use) against enemies who have +4 or so to hit and hit for 5 or more points of damage. How has the challenge been reduced?
And what exactly does any of this have to do with bringing characters to life? In that respect the strongest part of 5e seems to be its Background system.
I want to use AD&D as the standard. I think the core rules for 5th Edition should have set the challenge and power levels to this, so I want it to be brought back up with ability score generation and brought back down (where applicable) in the case of dragons being too powerful. These are my preferences anyway.
The reference to bringing characters to life is one benefit of random ability score generation with a wide field of outliers, such as given by 3d6 in order. In this way, the world comes to life more because it provides for more different kinds of characters, which is closer to reality. I could have fleshed out this point more.
I don't know how, but we have to get back to AD&D.