Since I realized I made a wall-o-text:
tl;dr:
Combat roles exist and are worth acknowledging. The same is true of non-combat roles. While classes may lend themselves better to certain roles, the archetypes the classes fill are generally orthogonal to game roles. Confusing the two is a bad idea and detrimental to the game.
I get what you're saying, but IME, 4e is super clear, and even explicit IIRC, about party role having nothing to do with how you roleplay the character.
My problem with the 4E roles was that they were all combat roles and every class had to fill one. I object to the game being balanced primarily around combat. Yes, combat balance is an important element of the game and should be balanced, however, it's not the only thing. I've played a number of characters, over the years, that kinda sucked in combat -- including a pacifist built as a Ranger specifically to avoid any sort of soft Controller or Leader (in the 4E buff sense; he was definitely a leader) confusion and a 2E Transumuter using one of the
Spells and Magic variants that made it hard to cast more than one spell in combat. Both characters were major factors in their games and often made the difference between success and failure (especially the transmuter), but almost never influence combat significantly.
The other objection I have is that, sometimes, a class fulfills more than one roll well. Fighters should be viable as both Defenders and Strikers -- they
fight and run the whole gamut of the term. A war Cleric is both a Leader and Defender; heck, the right build might even throw in some Striking or Controlling. The Warlock in our group could make a case for being a viable Defender because she has about 20% more hit points than the Fighter.
None of that means that the combat roles don't exist and/or should not be acknowledged. I'd rather not see them called out as "Rangers are Martial Strikers". Rangers
can fill the Striker role. A horde-focused Ranger build could potentially fill a light Controller role. There are enough people that see the Ranger as being hard to kill that I could easily envision a Survivor subclass that would turn it into a Defender. The elven Fighter in my group is more of a Striker, while the Life Cleric with the
heavy armor master feat is a fabulous Defender. These characters have secondary roles, too: the Fighter can still Defend and the Cleric is the primary Leader but the House Jorasco Wizard actually does an admirable job of playing Leader, as well.
Certain classes
tend towards certain roles, for sure. Trying to intentionally slot them, though, does a disservice. It leads to the grid view of "Martial Striker, check; Martial Leader, check; Martial Controller, hmm... time to write up a Razor Net Master class." Also, just because someone has a combat role doesn't mean they have to do it as well as someone else. The Ranger
shouldn't be as good of a fighter (small 'f') as the Fighter. The Ranger has other toys and non-combat roles to fill.
A better way of handling it would be to be aware of both combat and non-combat roles. The combat roles generally need to be filled, but I've seen a
ton of groups get by in every edition of D&D without a Leader/Cleric, for example. Maybe you even need three types of roles combat, social, exploration. I'm not sure what those would be, exactly, but it'd be interesting to nail down. The Face is the most obvious Social role, though the Observer (focus on Intuition) also makes sense. For exploration, the Infiltrator (get in and out of places), Watcher (diviners, scouts, and other info gathering), and Guardian (counter measures) all make sense, but those are train of thought and I won't defend them for more than example purposes.
You also have varying degrees of emphasis for each of the pillars -- let's say primary, secondary, and supporting. A Barbarian isn't as good of a Defender as a Paladin, but works in a pinch. Maybe you don't need a dedicated defender if your party is a Barbarian, Ranger, Light Cleric, and Dragon Blood Sorcerer. Each of those could be said to have Defense as a secondary or supporting role. Likewise, a Bard, Paladin, Ranger, and Favored Soul are going to be fine without a dedicated Leader.
The exploration/social roles should similarly be covered. My PCs excel at Infiltrator and Guardian roles, but are completely without any Watchers, so they don't know where to sneak into next and lay down some pretty indiscriminate wards every long rest, causing the game to really drag at times.
Just because a character doesn't have primary focus in one of the combat roles doesn't mean they lack compared to the other characters. My group is so heavy on Defense, Striking, and Leading/healing that they barely need Control. They'd benefit tremendously if their Evoker swapped out for Diviner -- or if either the Cleric or Evoker swapped around spell slots a bit. Even a purely exploration based character would get comparable spotlight and accolades to the combat champs.
