Let's look at things from the monster's point of view. We'll calculate the average number of hits "N" to kill a player character (of the same level) and see how it scales when the level goes to infinity.
For this analysis, we'll ignore healing surges and stat increases to CON.
For the player characters, the hit points H scale approximately as:
H = *constant* + CON + CLASS*level
where *constant* is a number between 6 to 10 (depending on class) and:
CLASS = 4 --> wizard, invoker
CLASS = 5 --> cleric, druid, ranger, rogue, bard, sorcerer, warlock, warlord, shaman
CLASS = 6 --> fighter, paladin, barbarian, avenger
CLASS = 7 --> warden.
For the monster damage, the average damage from the "normal damage expression" table on page 185 of the 4E DMG1, follows approximately:
low damage: 6 + level*5/12
medium damage: 8 + level*7/15
high damage: 10 + level*3/5.
(These were found by doing a simple linear fit to the average values).
Calculating "N" for the monster attacking players and scaling the level to infinity, we get:
low damage: N -> 12*CLASS/5 = 2.4*CLASS
medium damage: N -> 15*CLASS/7 = 2.14*CLASS
high damage: N -> 5*CLASS/3 = 1.67*CLASS
For the new monster damage table from the 4E DMG1 errata for page 185, the average damage follow approximately:
single target: 8 + level
two or more targets: 6 + level*3/4.
Calculating "N" for the monster attacking players and scaling the the level to infinity, we get:
single target: N -> CLASS
two or more targets: N -> 4*CLASS/3 = 1.33*CLASS.
Compare the old damage scheme to the errata update one. For the average number of hits "N" of a monster killing a player character, it is suggestive the errata updated monster damage is a lot more formidable.
Using the new errata monster damage, for example a monster fighting a typical defender player character, it takes around 6 to 8 hits to kill the defender without any healing surges. Using the old monster damage table from page 185 of the 4E DMG1, it would take the same monster around 12 hits to kill the defender (without any healing surges).
In contrast from previous posts which calculated the scaling for non-striker and striker player characters, we calculated that a non-striker player character would take around 8 to 10 hits to kill a skirmisher monster using weapons with damage dice d8, d10 or d12. A striker player character would take around 6 to 8 hits to kill a skirmisher monster using weapons with damage dice d6, d8 or d10.
Indeed, the old 4E monsters using the old damage scheme from page 185 of the 4E DMG1, don't appear to be as much of a threat to the players (even without any healing surges). A reverse "always fighting orcs" where the "orcs" are consistently losing to the player characters.
In contrast with the new damage scheme from the 4E DMG1 errata, the "orcs" can actually win sometimes against the players.