And here is my point: they should develop on an individual basis, not as a general level scale. it`s unreasonable that because YOU are better, all others are also better (and that also spoils the fun of getting better). They should level on the same rule as you do: using their skills. And if you are leveling at a slow pace, maybe others would level faster (would be a matter of choice). Always there should be low, mid and high level character, except they would dynamically rotate through leveling (after some time spent at highest level, a low level character would replace it). Leaders should always be at some degree of high level.
I would say dungeons should not scale. there should be different kinds of leveld dungeons and you should be pointed about their level by other characters. if you go there by youre self, it`s all on you.
I do understand there should be a way to maintain balance and provide either challange and possibility for every quest at every level. but that`s either not true: you shouldn`t pursue a way for witch you do not possess the means, beeing a quest item, or a quest completed before or why not the appropriate skill. as it is now, if you do not have the appropriate quest item, you are not given the quest or you are pointed toward obtaining it. it should work the same for skills and level also. you should pursue a way for witch you don`t have appropriate level, a character along the way should point you toward working out some particular skills or simply get more experience. you also hshould have tactical aproaches: should you have tons of money you can buy invisibility postions and work your way or hire a bunch of tough thougs to do the work for you, etc.
here I would say skill points are not to my liking.you should have the option to spend more points toward some skills in the detriment of others. this way, you can start with high combat skills and don`t even posses magical abilities and this offers you the means to do all fighting quests. the trick here is to have to choose your skills carefully, as you can`t obtain all. maximizing in one direction should constrain you in getting decent skills in another.
different aproaches should have benefits and disadvantages. I liked infamy system in oblivion. this should be back. a thief, known to be one, should loose in speech skill. an assassin, known as one should lose in sneak skill. killing someone and be seen should make you feard and so characters will aproach you less.
and again, quests should be designed to match all kinds of skills, not mainly combat (as we have magic, stealth) and also almost any quest should be aproached in different ways like open combat, stealth, assasin, magic, etc. Example: you have to take out a character because he stands in the way of your employer. you can kill him (by open fighting him, by killing him while he sleeps, by assassinating him from distance) or you can threaten him with killing and he will behave as you tell him. or by taking him out of bussines (like stealing his assets, killing caravans so he doesn`t get his supplies, compromising his bussines, etc.)
all these that I wrote here should make you choose a path. should force you decide the benefits AND disadvantages of your way and so to gimp you by default.