I think what you're seeing in the higher-level DCs being "easier" is the increasing gap between Trained+Prime Score and Trained+Dump Stat and Untrained as the characters level up.
A fighter who is trained in Athletics is going to start with a good bonus because he needs a good strength score. And it will improve at a rate faster than +1/2 lvl because the fighter is improving his strength as he levels up. A +9 bonus at level 1 might be a +28 bonus at level 30.
That same fighter can be trained in Intimidate, probably starting with a middling bonus because he has no particular use for charisma outside of that one skill. But his charisma barely improves with levels (+1 at 11th and 21st lvls). A +6 bonus at level 1 would be a +22 bonus at level 30, and even that is somewhat generous in assuming an above-average stat allocation.
Untrained skills will vary between +23 (better than trained+dump stat) and +15 at level 30. So the DCs have to have more slack built into them to account for non-prime skill uses.
A fighter who is trained in Athletics is going to start with a good bonus because he needs a good strength score. And it will improve at a rate faster than +1/2 lvl because the fighter is improving his strength as he levels up. A +9 bonus at level 1 might be a +28 bonus at level 30.
That same fighter can be trained in Intimidate, probably starting with a middling bonus because he has no particular use for charisma outside of that one skill. But his charisma barely improves with levels (+1 at 11th and 21st lvls). A +6 bonus at level 1 would be a +22 bonus at level 30, and even that is somewhat generous in assuming an above-average stat allocation.
Untrained skills will vary between +23 (better than trained+dump stat) and +15 at level 30. So the DCs have to have more slack built into them to account for non-prime skill uses.
FireLance said:The math behind skill challenges bothered me too. Then, I looked at the higher-level DCs and noticed something interesting (numbers from pg 42 of the DMG):
For levels 1-3, a moderate check was DC 15 (DC 20 for a moderate skill check).
For levels 28-30, a moderate check was DC 29 (DC 34 for a moderate skill check)
A 30th level character would have a +15 for level, say a +6 from ability scores, a +5 for skill training, and an unknown amount from magic (I haven't digested all the powers and magic items yet), for a total of +26. A trained character would thus succeed 65% or more of the time on an individual skill check, making it more likely that he can overcome a skill challenge without assistance.
So, the skill challenge system for 4e seems to require characters to work together (using Aid Another) to have a decent chance of overcoming the skill challenges at low levels, while allowing them to function more independently at higher levels.
So, what do you think: bug or feature?