I understand that. I am just puzzled that with SUCH a power level discrepency that the encounter is not an immediate slam dunk. I would love to pick the designers' brains and find out the reasoning behind this design decision.
To begin with, 4e characters receive a substantial portion of their overall hp at 1st level (in contrast to 3.x characters whose hp increase a little more linearly if one assumes the average). At 3rd level a 4e fighter with 16 Con will have 43 hp, in contrast to the same character in 3.x having (assuming average rolls) 30 hp.
Only a 13 hp difference admittedly, but consider that 4e started with 31 hp whereas 3.x has only 13 hp at level one (an 18 hp gap that narrows by 5 after only 2 levels). Their hp progression curves are significantly different, which influences how much damage is "appropriate" at later levels.
Secondly, that the 4e dragon will drop the 3rd level fighter in the first round is almost guaranteed (Breath Weapon + Action Point + Double Attack for 51 average damage), he just doesn't go about it in exactly the same manner. There are a number of reasons for this.
For starters, 3.x dragons assume that you have some form of applicable energy resistance like Protection from Energy (or some effective equivalent like the Cloak of Resistance + Ring of Evasion combo) if one intends to slay them. This is something I read from one of the designers (I think it was Monte Cook). 4e does have some limited damage resist effects but nothing even comes close to Protection from Energy, hence 4e does not account for such resistances.
Then there is the fact that the dragons output damage differently. The 4e dragon uses his breath weapon as a free action the moment he hits 50% hp. He also has 2 action points to use during the encounter that give him a free standard action (which he can use to Double Attack). Basic 3.x dragons could
either full attack
or breathe. Three times during a given encounter a basic 4e dragon can Double Attack
and breathe. I think it rather obvious from this that if you gave 4e the same damage as that of 3.x, that he'd become a virtually guaranteed TPK.
Finally, the 4e dragon has 750 hp, as opposed to the 253 (average) hp the 3.x dragon has, so 4e may have two to three times as long that he can beat on the party (obviously this ignores a lot of other relevant factors such as damage and status effects, so consider this an extremely crude theory rather than gospel). 4e paces it's encounters differently from 3.x. Damage and hp have been adjusted in order to make encounters longer (in terms of rounds) so that both sides have an opportunity to use more powers.
3.x and 4e each have differing approaches to combat. This, in turn, necessitates different approaches to class and monster design. IMO, each does an admirable job within it's own style niche, the preference of which is of course a matter of personal taste.
[ Disclaimer ]
I realize that these comparisons may border dangerously close on "edition war", but in all honesty that is not how they are intended and I ask that they please not be received in that manner. The OP's question related to why these two creatures are so different, and I could not think of any clear means of explanation without using the two creatures themselves for comparison, which in turn requires some degree of examination of the base assumptions of the systems themselves.
[ /Disclaimer ]
