The issue of hit points reminds me of the time Gygax was asked about them, and his response was along the lines of: if you have a fighter with 100 HP, and he is whittled down round by round from arrows, the fighter isn't just walking around with 25-30 arrows sticking out of him until one eventually shaves off that last HP. No, he only takes
one arrow, the one that drops him below 1.
There is a thread recently wher M. Cook used the term "lurker" and there was twenty or more posts here debating his meaning of the term. Was it the actual creature named the lurker (aptly named) or was it an "ambusher?"
Had it not been called lurker, but instead ambusher, then you'd get arguments that "Well does that mean that you can only use them in ambushes? So you're limiting how it can be used? So what happens if they're not in an ambush situation - does the monster cease to be?" and so on.
Regardless of what word was chosen,
someone would have had an issue with it. For example, why do we call the fighter a "Fighter" when
all classes
fight, and they fight with the same frequency as the Fighter? And most melee classes are just as competent as the fighter. How about the barbarian - that denotes a certain cultural expectation,
and it has quite the negative connotation! The class implies that a character must be a primitive - can't you have someone in the barbarian class from a city? And don't even get me
started on Thief or Rogue!
The "Leader" role is basically "support". They buff. They grant extra attacks. They heal. Essentially it's maximizing the potential of other characters. But calling the role "Support" would have been a bitter pill to swallow;
most people don't like it implied they're a side-kick. "Leader" is more positive a word than "Support", and they are trying to entice people to play leaders because in all previous editiosn D&D, someone has always had to play the healer.
Saying "why do we have to have roles spelled out at all" is like saying "why do we have to spell out classes at all". Those roles have always been implicit. Thieves just
don't stand in the front lines (well they
can, but they don't live long when they do). Fighters just don't buff. The only difference is that 4e pulled back the curtain and drew it into the light, designing classes to focus on what they've always done (and how most people have played them). I've been hearing "we need a tank" as far back as the 3e days.
Role is also a way to simply categorize mechanics. Look at 3e. There you had classes that received a +1 to BAB every level (fighter, barb, ranger, paladin). You had those that received a +1 every other level (Wizards, etc) and those that were somewhere in between, with a BAB progression behind melee classes but not as bad as wizards (rogues, clerics). That sounds like a systematic method of their mechanics. If those groups had received a name, then that would be similar to categorizing them in roles based on mechanics. With 4e classes, roles have predictable HP /Healing Surge/Armor proficiency expectations.