However, because (in 4E for example) the numbers to PCs skills creep so high that as Ryujin said... by mid-Paragon a good PC no longer needs to roll to succeed. Thus we've lost a possible avenue for dramatic tension.
Of course, there's a question that hasn't been asked: if we're at a level when most PCs can fly, should climbing remain a valid challenge at all? Or should it instead be assumed that a skilled PC can just succeed at anything but the toughest climbs?
The only other option therefore is to make the DCs for climbing fluid... so that as a PC becomes more skilled, they still are required to make Climb checks. But at that point we get the situation where a wall that was a certain DC at 1st level has now morphed into a wall that is this new higher DC... not necessarily because the wall is more difficult, but merely because the DM wanted to present a challenge to the PC.
If it really is the same wall, then that is indeed stupid. And probably bad DMing/bad adventure design.
However, if the wall that the PCs have to contend with is, indeed tougher, that's a rather different matter. Which brings us to...
(unless the DM tries to get around it by taking standard DC walls and then modifying the DCs by throwing all kinds of oils, wind, darkness etc. etc. in attempts to raise the DCs so they present a challenge... but at some point when every wall is like that, it becomes kinda stupid).
Indeed. The key here is that most walls
shouldn't be like that, and the PCs
should be able to succeed even without a roll. By and large, climbing should just cease to be a problem at those higher levels. It's only when faced with a climb that is somehow tough (no equipment, a strange construction, extreme time pressures...) that they should have to roll.
But that's a feature, not a bug.
It's a catch-22. How do you create DCs for non-supernatural events that don't become obsolete at some point because a PC advances past it?
You don't. You recognise that PCs, once they reach Paragon levels, are
superhuman. They're the guys who
can climb anything but the toughest walls, who
can swim a moat in full armour, who
can arm-wrestle an ogre and win.
So, if the challenge is "climb this mountain", the PCs do it. Don't even bother to roll. They just do it.
But when the challenge is "climb this mountain in the next three hours, while being buffeted by heavy winds, while carrying the unconscious princess on your shoulders, and while the mountain actively tries to throw you off..." Yeah, you have to roll for that!
And what kind of challenges can you throw up instead that don't involve either heaping all manner of ridiculous modifiers to try and make the action more difficult. Or how do you explain away the changes in DC that come not from an action actually being more narratively difficult, but rather just from a fluid DC table put into place to keep the "dice rolling game" an active part of D&D throughout all levels?
The more I think on it, the more concerned I am that the concept behind the escalating math just doesn't work. Mathematically, it's fine - the PCs roll d20 + mods versus a DC. And the mods go up with level (of course - the PCs are better), and the DC goes up with level (because they're facing what is genuinely a tougher challenge).
But it too easily boils down to this: "At 1st level, I roll d20+5 vs DC 15. I need a 10+. At 11th level, I roll d20+15 vs DC 25. I need 10+. At 21st level, I roll d20+25 vs DC 35. I need 10+." That has the potential to become tiresome
very quickly.
I find myself wondering if maybe it's not enough for the math to simply escalate. Perhaps, as the game moves into a new tier, we actually need an entirely different set of resolution mechanics, to freshen things up? (Of course, I have no idea how that would be done, or what it would look like!)