In a scene based game yes. In a goal based game that wall would be appropriate for a well made town or castle wall while raining. If the PCs happen to be level 10 when they try to climb it is a different matter.
Again, that is scene based design. The door is reinforced because it is supposed to be a worthy challenge for the PCs of the current level. In a goal based game the door is reinforced because it is a important door.
I just don't know where you get this from, to me what you're saying simply makes no sense. When a DM devises adventures he most certainly devises them with some idea in mind of what level of PCs will be adventuring in them. I know there are these people that swear up and down they run a 'perfect sandbox' and the PCs just wander around at will and run into whatever, but it just doesn't ever happen that way. DMs put most of their effort into certain parts of their world and both they and the players are usually trying to figure out how to get the characters into the fun and interesting part and NOT into the boring and ridiculously pointlessly deadly or trivially easy part. Nor are you likely to have pregenerated a whole campaign worth of sandbox, you invent new stuff as you go along, the PCs move into new and 'higher level' areas, etc. This means that the GENERAL pattern is that PCs are in level appropriate challenge areas most of the time.
Moreover, as I've said several times over already, there is no reason why 4e or 5e characters do different things from 2e or 3e characters. In all cases it is quite possible that now and then players will engage with some specific challenge that is of some other level than their own, usually easier, but now and then lower level PCs WILL get thrown some weird ultra-challenging check. I see no reason to believe this won't happen in all editions. It may happen more or less (maybe even not at all) depending on your style of DMing, Pemerton may well only run into that in a situation where PCs reprise a previous situation (can happen especially in towns, but not too often), and it would be rare. You might encounter it somewhat more often in your highly sandboxed game, perhaps. The point is you could be using 4e rules and Pemerton could be using 2e rules and it would still be the same thing.
Which means all doors the effectively encounter are adamantium as all others aren't worth mentioning. Besides this is exactly the advise 4E gives you (at least at the beginning of its cycle)
No, all 4e does is point out that simple wooden doors will not challenge an epic party. They may well EXIST, but they're either set dressing or effectively terrain (they can block LoE/LoS, take an action to break through, etc). There's nothing wrong with this. You're playing Gondzog the Mighty, Terror of the North, 26th level Demigod, your story is about hewing through the links of the chain which holds the world in place, not breaking down the flimsy wooden door to Orcus' loo.
Or the problem is that we have a different idea what is "genre appropriate".
It wasn't about specific genre appropriate things. It was about knowing WHAT IS the genre appropriate thing in a given setting.
It is basically the same scene based setup like in 4E where every character has a chance to do everything, training or not. The only difference between 4E is that instead of both scaling skills and DCs (for a net difference of 0), nothing is scaled at all.
But that's a big difference and that was exactly what I was questioning the value of. They aren't the same. IMHO 4e is avoiding a serious pitfall there, and one that is much more relevant than the corner case where it should be hard for the 25th level wizard to pick the door to the level 1 lock on the Mayor of Squatville's hovel. Even if arguably that might reasonably still be hard for that wizard, its just not coming up.
Actually players were required to do just that when 4E first came out. There was no backing out of skill challenges. It likely has changed by now, but this initial version shows how 4E was designed.
No, they were never required to roll. The very first version of the SC rules had players rolling initiative and deciding their actions in order, you could still do nothing if you wished. However this whole view of SCs is rather flawed, and even the original DMG1 SC text makes it quite clear that an SC is a dynamic situation where different things happen based on the narrative. A character can 'back out' potentially in many ways, but its not guaranteed that the opportunity will exist, some situations have their own momentum. So yes, if a character is steering a boat down a gorge then she probably can't opt out of steering past rocks. OTOH if the characters are having a go at cracking a puzzle lock on a tomb then its pretty much OK if one character steps back. It would be IDEAL however if there's some other element to the challenge said character can engage. Once in a while maybe there isn't, if the scene isn't going to be long and drawn out then a simple challenge can quite readily be handled by one or two characters. The point is if those one or two characters don't happen to be there, or don't exist at all in the specific party (say its a module you're running) then its not a disaster, the PCs you do have can at least try to muddle through. Maybe if the players are clever they will have even equipped themselves in some special way to cover that weakness. I also don't see anything in 4e that indicates that there can't be easier paths to travel, etc. Normally however it makes sense if all paths are at least within the same ballpark of challenge lest you risk anticlimax.
