My own personal opinion is that the rule is actually a good thing, and I enjoy it.
How can one "enjoy it"? That's a sort of baffling assertion without explanation in this specific instance.I could try to guess, but I don't want to put words in your mouth.
From what I can see, a good chunk of your arguments appear to be built on the assumption that the rule is purely in place to prevent certain powerbuilds. While this is surely part of the idea (I didn't write the rules, so I can only guess in the end what the full intentions of the authors were) I'd say it serves other useful functions as well.
My arguments are based on the rule's given justifications. How else should I respond?
For one, it means that you'll have to do your "dip" (or at least part of it) earlier on in your character's lifespan.
RP is in no way synonymous with "dipping." It makes no more inherent sense to say a character development goes 2+10, then 10+2, as I already said. This is a mechanical argument that has no basis in RP. It is just as easy to have a character RP fiddling around for a couple of levels as rogue and then suddenly transforming into a mage as to have a mage for several levels who later in life--perhaps because of not having the intelligence to master high-level spells--deciding she will apply that intelligence to things like lock-picking.
Given the compression of time on the server, it's even less valid to make such a distinction as almost all PCs have "lifespans" on the server in the single digits.
Certainly there's nothing magical about the number 10. And regarding PrC, then why would you have prerequisites? Once more, a cleric cannot even take a level in DC before 10th. There is no possibility of early "dipping," which, aside from the mechanical perspective, demonstrates the game designers didn't share your view that characters should "from conception" know everything they might do eventually in life.
I'm not sure what the first statement means, but the second one is mostly covered with my points above I feel. Mastering something (reaching the higher levels in a class) should take a lot more time and effort to do than becoming an amateur. Another analogy is the runner or weightlifter who used to be out of shape. When he's very overweight, he loses weight and makes big gains very quickly because it's easy. But to refine your physique to bodybuilder competition or competitive marathon runner practice, it's going to take a lot more dedication. This makes logical sense to me.
Pelor almighty! Do you think I'm arguing that levels should all require the same XP? No, I'm pointing out that dipping is on the cheap at low levels and highly costly at high levels. That's why rewarding it at low levels and forbidding it at high makes no sense in terms of the stated goal of the rule.
So it's reasonable to believe that after a certain threshold (say, level 10) a character no longer has the time, energy, mental focus, or whatever else to take up learning an entirely new field of study.
This goes against what you earlier said and against the XP cost associated with leveling.
Assume a 12th level wizard PC. She needs 12,000 XP to go to 13th level. She can expend those XP to become a 13th level wizard or a 12th level wizard/1st level rogue. Do you honestly believe if she expends 12 times the amount of XP to achieve that, she can't possibly master those basic skills? It boggles all common sense to think that advancing the extra level in wizard is easier then picking up the basics of being a rogue when the XP cost is so disparate.
I'll leave aside that the 1st level rogue gets 4 times as many skill points as the 12th level wizard will get for her 12 times as many XP because that's true only in this specific example. But this is why I say a level isn't a level. The higher you are when you make your dip, the more XP (and time) you have to expend to get the same reward as the lower level dip would have cost.
Your argument about "maintaining" current skill has no IG basis. There is nothing in game requiring us to do anything to keep our skills from rusting. If that's how you like to RP, fine, but don't force your interpretation on me
Legion raises an important point--it's often that a one-level dip is for purely power reasons and is not roleplayed as an aspect of the character.
Ummm...I think he kinda said the opposite. He multiple times said my view was limited about the rule as far as cheesing and (to quote his actual words): "Again, this is basing everything on the assumption that this rule is in place solely to lower the 'power' of available builds, which doesn't seem correct in my own opinion."
Regarding re-leveling, that's a cure that's worse than what the rule is supposed to prevent. If the goal is that the character RP excellently throughout her gamespan and develop organically, then
deus ex machina fixing her isn't an optimal solution.
As for PrCs being rare, this rule has no correlation with that goal--a goal easily achieved by the application process, anyway. However rare the CC thinks they should be, the CC has absolute power to make that happen.
This rule, instead, forces players who want to do a PrC to go about it a certain mechanical way, but it can't by itself stop anyone from getting the class. Anyone can plan ahead. And if they don't, as you point out, they can ask for a re-level.
The major effect the rule accomplishes is making level accumulation follow a prescribed pattern, which isn't demonstrably better than any other pattern, for arriving at the same destination.
The real reason to support this rule is if you believe at level 11 all characters who have focused on one class should stop being able to go in a new direction. (I think it's fair to read Legion as saying he believes that.) If you support the rule for other reasons, those reasons are generally unnecessary as other means are in place to enforce them more effectively.
Many times I've read the high-uppities here say players focus too much on builds and should let their characters go where they will. It's a mixed message , then, to say halfway through your levels (and much less than halfway through your career), you can't make a career move to try something different.
Because no one addressed this, I'll repeat it: Prestige classes should not be only the ambition of a brand-new character. They should be something to shoot for when a high level starts looking for something to cap her career with. I don't think it would happen that much, actually, because (as I keep demonstrating) the tradeoffs mechanically aint that great for a high level versus a low. But it would provide character motivation, a goal, etc.....the things that make for dynamic RP, rather than the static view of character Legion embraces.