The dice rolling method is cool. Some of the game should be "luck"
I agree with this to a point. My big problem with crits is that a low level character lacks the survivability to sustain one without dying, particularly with a x3 or x4 weapon. So, it's not that they could die in the fight that bothers me, but more that they could
die in one hit before they get a chance to act.
DM: Okay guys. Roll initiative.
Player 1: I rolled a 9.
*other players roll*
DM: Okay, the orcs are going on 18. One of the orcs attacks you, Player 1.
*Rolls a 20. Confirms with an 18. Rolls average damage of 6+6+7+12.
DM: Okay, you take 31 damage. How many HP did you have?
Player 1: ... uh, 12...
DM: So you're at -19 HP. Roll up a new guy.
To me, that isn't fun. And something to remember regarding "luck": The PCs are around for the
entire campaign. The monsters are around for
one fight. So, saying that it's okay to just die if the other guy rolls a 20 followed by a high number sucks for the players. They have to endure far more of those attacks than any given monster. After 30 to 50 attacks, they're statistically very likely to suffer a confirmed crit on a natural 20. If that crit can one-shot them, it gets pretty tough for characters to survive for more than 50 attacks without DM fiat. Hopefully they gained enough levels by that point to live through it!