I was originally going to reply to a comment by Graham, but as it grew, it got too big, and began to become worthy of an actual post.
Answering what will be forever remembered as the "Ham Sandwich Argument"
I mean, if I had 100 types of ham for a sandwich, and I could put any 10 of them together for a sandwich of awesomeness, that would be great and would result in a lot of different-tasting sandwiches.
If I had 1000 types of ham, though, it wouldn't result in significantly more tastes of ham sandwich. Each of those additional 900 flavours of ham is going to taste pretty similar to one of the existing 100.
Even if I was able to use 20 different ham types for my sandwich, all the added flavours would begin to blend into each other, or would be there in such small quantities so as not to affect the flavour in any meaningful way. 4e decided to have fewer, more distinct types of ham. And by only combining two (one with a taste of the other), each type you have on the sandwich adds significantly to the flavour.
I have a small issue with this analogy, it's this; When making a 3E "sandwich", one only uses 1-4 different kinds of ham (unless they are a fool). IMO the best sandwiches are made from 2-3 different kinds. Yes, there are thousands of different types of ham, but how many actually get used for one sandwich?
Now how does having the deli manager come out and tell you that due to a perceived overhamification, they are now only stocking 12 types of ham, and you may have no more than 2 different kinds...period. Unless of course you want an "epic" ham sandwich, if you have the patience to sit through it's grueling construction, you can choose ONE more piece out of the "special" ham drawer. I've never been a fan of limiting option for more fun...it feels oxymoronic to me.
Don't get me wrong, I bet at least 3-400 of those other hams are terrible, or don't go with the mustard, or whatever, but that doesn't mean I shouldn't be allowed to try them does it?
Now that I'm done "hamming it up", we'll go to your first question.
What would you say is required to make someone a "rogue".
Now, forget class names here. Why does someone need to have the Rogue class to be a Rogue? Was the 3.5e Ninja not rogue-ish? Even the Bard was pretty rogue-y.
What is required to be a rogue? And why does it matter if you have the class title in the first place?
Excellent question, but it is difficult to answer. A portion of it is down WAY below. The easy part first. You need the rogue class to be a rogue, because fighter can't be stealthy worth a damn : ) It is focus primarily, identity secondly, and flavor tertiarily. These three words are the reason for existence of all the classes out there (and to a lesser extent the PrC's as well). These concepts are woven into the very fabric of the game.
Let's put it another way; what makes a striker, a striker? The PHB says, mobility and high offensive potential...how does this say ranger or rogue? They sneak and track too, but where is that mentioned? Wouldn't a fighter with a 2H weapon fit this too? A wizard "properly" played in the back rank? A smiting paladin? Why should my role be tied inexorably to my class and style of play? This brings up powers, the meat and potatoes of 4e. The reason those won't work out are because the powers structure is built specifically to enhance the single role your character has been fitted for.
This hearkens back to the olden days of D&D, when nobody but humans could be paladins, or only elves and dwarves could actually multiclass. Why? Because it was in the rules. The difference now, is that the whole game is now built around the concept.
Moving on, I'd say the difference between similar classes (Barbarian/fighter/Paladin or Bard, Ninja, Rogue) is focus. I mentioned it above, but here we see it come into play. Ninjas and bards are NOT rogues, they are core (and expanded core) classes that overlap somewhat within the rogue's sphere of influence. They share some skills, and a few mechanics, but they are not built to be trapspringers, tomb raiders, or (arguably) burglars. They are uniquely different using the same set of core class mechanics. Examples, bardic music/knowledge, ninjas and bards get spells, sudden strike vs. sneak attack, granted abilities (ninja) that have no roguish analog, different skill point bases, different class skills.
Class title gives a (hate to use the word) generic outline of a character concept at the outset of the game. You would pick a rogue because you want to sneak around, be an opportunistic damage dealer, play a skills based character, or simply want to steal things. None of that says "striker" to me.
I would ask you, why have a "role" title at all instead? Does my "role" define my gaming experience any differently than my class should? Why can't I have a striker warlord? Or a leader wizard? What single feat or power that I trade for will make me this? How many will it take? I'm never gonna be a fighter/rogue, I'll be a fighter, with a couple of rogue skills, or a rogue who handles a sword a fractional amount better. How is this useful multiclassing?
I don't think it is very realistic to try and strip the "class" out of the question. It is integral to 3e mechanics. We'd have the same problem trying to strip the roles out of 4e, it is part of the core mechanic as well. This leads us to an apples and oranges comparison, which is impossible to really discuss. IT will come down to liking oranges tart goodness vs. Apples crunchy goodness - similar, but not enough to draw an actual comparison too. Better just to enjoy the fruit eh?
This was a fun post to write, and my cubies probably think I am insane from all the stifled giggles over here : )
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