I am not on the AU bashing bandwagon. And I know how to spell "nor". However, really have to call you on this:
None of those games are more lethal than D&D.
This is, flat out, wrong.
By design D&D is less lethal than multiple of these games. In D&D, the average encounter is explicitly designed not to have a chance to be lethal, but to consume party resources. Check out the DMG if you don't beleive me. It discussed this explicitly.
In contrast, in Cyberpunk and in Twilight 2000, any conflict with lethal weapons has a very real possibilty of leaving a character permanently injured or dead. It is a whole different paradigm.
In D&D, a 1st level anything has a good chance of getting killed on a critical hit by virtually anything.
A 1st level character has maximum hit point. Most CR 1 encounters do maybe 1d6 or 1d8 points of damage for an average around 4, 8 on a critical. Typical weapons only threat on a 20, and given an AC of 15 or so, only crit on 25% of threats. Most characters will not be knocked into negatives by such a hit, and even those who are will only be at -4 or less.
Contrast this with twilight 2000 where
any hit is likely to disable or kill.
In D&D, a 5th level anything has a good chance of getting killed by the average fireball if he or she fails his save.
A 5th level character has, on the average (assuming 10 con -- a conservative assumption in most games) 14 (wizard) to 37 (barbarian) hp, and the average fireball at 5th level does 17.5. Even the wizard will only be knocked to -4 on a failure, easily in "saving range". A barbarian suffers less than half HP loss. Your assertion is false.
Consider that in games like twilight 2000, every gunshot can do a comparable or worse amount of damage compared to their damage capacity and has a magazine full of these things with automatic fire as an option. A fifth level wizard might have two fireballs.
In D&D, a 10th level cleric can almost always force a character to save or die.
By which time raise dead and death ward are available.
D&D is a very, very lethal game. Contrary to popular belief, hit points don't make a game any less lethal.
False. The fact that HP are so large in comparison to the average damage is precisely the reason that D&D is less lethal than other games. Again, by design.
As for how this pertains to AU: obviously Monte felt that he wanted something in which ressurection magic was a little more inacessible than the all-too-generous D&D, but he obviously did not want to make it into Cyberpunk or Twilight 2000.