I'm not sure I agree with that purported design goal, and in addition, AD&D's multiclassing rules allowed you to be both a warrior and a spellcaster, switching between them on a round-to-round basis.
In any case, you're correct that 5E has a design goal of enabling casual play, and long spotlight cycles are incompatible with casual play. I think your observation is correct w/rt 5E's design goals; I just don't agree that those goals are normatively superior.
Fair enough. Implicit in my statement was that I think these are the correct goals
if you want a broadly appealing game.
This is where I have a problem.
Why must you be able to do max damage in order to feel awesome? I have never ever seen a ranger that might as well not have shown up just because they weren't fighting their favoured enemy. The whole point of Favoured Enemy was to give the ranger that extra flavour and to give that flavour a mechanical distinction.
Okay, so is favored enemy the core of the ranger's identity, or is it just "extra flavor"? Because I thought you were saying before that it was the core of the ranger's identity. If it
is the core of the identity, then yeah, when you're not doing it you don't feel awesome. Wizards don't feel awesome when they can't cast spells - not because they're weaker, but because the player rolled a wizard in order to fulfill a spellcasting fantasy. Barbarians don't feel awesome when they can't rage and smash faces - not because they're weaker, but because the player rolled a barbarian in order to fulfill a rage-monster fantasy. So if what you're saying now is that rangers
do feel awesome when they aren't fighting their favored enemy, this tells me that players don't roll rangers in order to fulfill a favored-enemy fantasy, that favored enemy is not the core of the class' identity.
Now, yes, I'm aware that doing something like separating the wizard from his spellbook can make for an interesting adventure if it is run well. But adventures like this are the rare exception, not the norm. Furthermore, the primary goal of the wizard in such a situation immediately becomes "get my spellbook back or acquire a new one", which is engaging, in character, and drives the plot forward. Separate the ranger from her favored enemy, and what do you get? "Let's get out of here as soon as possible and find some giants to fight"? The wizard's spellbook tells the character to be more engaged in what's going on, but the ranger's favored enemy ability tells the character to be
less engaged in what's going on.
You must also account for the fact that not every DM can run such a curveball adventure well. You say you tailor adventures to PCs, and that's great; I try to as well. But the implication I'm getting from you in this conversation is "Everything will be fine if only every group plays the game the same way mine does", and every group does
not play the game the same way yours does. There are many different styles at many different skill levels, and I think the game should, insofar as it is possible, support all of them. In particular, I'm thinking of people who participate in organized play, or run published adventure modules. These games are very common. They should probably be accessible for a very popular character class. And by "accessible" I do not mean "You can show up, but you're just going to be a weak fighter because there are no giants."
Here's the problem: If you make wilderness survival the focus of the ranger class, then the only campaign where rangers are fun to play is the one that is constantly traveling the wilderness. If the party spends a couple of sessions adventuring in a city, or exploring a deep dungeon, or traveling the planes, or whatever, the ranger spends those sessions as a sub-par fighter.
I think this can be alleviated by interpreting the "wilderness survival" focus as "environmental awareness". No matter where the ranger is, he can figure out something to do with his surroundings. To anyone else, those weird mushrooms are just set dressing, but to the ranger they might be food, or bait for a trap, or a source of poison, or a hiding place. He's the guy who notices which sewers the rats avoid, and improvises a shelter out of a modron chassis. He is, in a word,
resourceful.
...which may be hard to capture mechanically.