Well, no. The chance of PC fatality is dependent on the difficulty level and the actions of the players. The rocket tag moniker again simply indicates combat that is fast and swingy, but that can still be slanted in the players' favor.
It is
also dependent on the rules of the game and how lethal things actually are.
Endless PC death sounds pretty archetypically D&D to me.
To me only if you play in some modes. It's almost anathema for Dragonlance and 2E - Dragonlance literally telling you to fudge the dice.
But it is discrete from it. Many games have no conception of balance at all. Others have purposeful and extreme imbalances. Balance is only really critical for pure games of strategy, like chess (which even then has purposeful imbalances between the pieces built in).
Balance is information. Nothing more, nothing less. An imbalanced game doesn't actually tell you how strong threats are. This is a problem.
And D&D is not a strategy game, it's a roleplaying game, to which balance between player choices is somewhere between a tertiary consideration and completely irrelevant. Only because of D&D's wargame heritage is it even mentioned.
The two are not mutually exclusive. D&D is a roleplaying game about players who prepare for then go into ridiculously deadly and unrealistic environments and scavenge what they can. That second part is a strategy and logistics game with life on the line.
So it's perfectly balanced and there's no system mastery. And it's a terrible game. The parallel here is pretty obvious: if 4e is what you say it is, it's pretty much the same.
Who says there is no system mastery to 4E? Whoever does is simply wrong. 4E did not
set out to reward system mastery. Unlike 3.X. This is because rewarding players for system mastery is like rewarding players artificially for being tall when they are playing basketball. The advantage of being tall on a basketball pitch is inherent. The advantage of system mastery is inherent. You can not get rid of it. Artificially further rewarding it through obfuscation is like giving more money to the people who are already rich and taking from the poor to fund it.
Of course, though it has its limitations, not everyone thinks that Chutes and Ladders (or 4e) terrible because they're deriving enjoyment from something other than the exercise of skill to sway the odds in their favor.
In both 3.X and 4E I derive enjoyment from the exercise of skill.
In 3.X I derive enjoyment from the exercise of skill
in character creation. But I end up feeling as if I need a shower afterwards - the ways to build a strong character are well known and obvious (spells > mundane, ability to pick saving throw targets is huge). I also derive enjoyment from
efficient tactical play - how few spells can I win the battle with and how little will it take to rig the odds in our favour.
In 4E I derive
more enjoyment from the exercise of skill in character creation because I don't end up feeling dirty because using my skill to either create an offbeat build or redline a build won't have me completely overshadowing others. Further I don't feel anything like as cramped when building a 4e character as when building a 3.X one. I derive enjoyment from
complex tactical play - using tactical positioning and exploiting both deliberately provoking the enemies and the scenery to completely change what is going on in a way I couldn't in different scenarios. I also derive enjoyment from
flamboyant tactical play; tactics I can tell my group hasn't seen coming because only a madman or someone who had an exceptional grasp of the situation would try. And efficient play in 4E involves taking the enemy down fast and at low risk rather than seeing how many spells I'm not using. (On the other hand playing 4E with a slow group drives me right up the wall).
Your claim that there is no enjoyment from the exercise of skill in 4E is simply false. I find there to be many more ways to excercise skill in 4E than 3.PF or 3.5 and it to be more rewarding when you do so.