Didn't rangers get Hide and Move Silently in 2e? And wasn't favored enemy much more limited than in 3e? I remember the 2e ranger for its combat prowess, occasional healing, and the fact that you could multiclass it with cleric for some reason.
That it did.
So, two thief skills, out of eight or so, and thieves no longer have a niche? Note, the ranger's skills were halved as soon as he left natural surroundings. More niche protection. And, let's not forget the nature empathy - another power that no one else got. Cleric spells didn't kick in until 8th level, so, not really stepping on the cleric's toes too much.
Again, how unique does a class have to be to be considered "niche protected"? I mean, in core, rangers got two weapon fighting, for free, which no one else could do without pretty serious penalties. That right there makes rangers considerably different from other fighter types. They had several unique abilities that no one else got like animal empathy, some serious (and I mean serious) followers, bonuses to a specific type of creature (a watered down ability from 1e where it was a much broader ability - something 3e brought back) and tracking with bonuses.
How much more does a class need?
I look at it this way. Mechanically, in 3e, you could make a fighter/cleric that was pretty darn close to a paladin. Might be a bit off, but, not too far. Certainly close enough for government work. Yet, it wasn't a paladin, because it lacked a couple of very key elements - Paladin's Code would be the big one for me, and the paladin's warhorse. Both are class features that no other class gets.
Barbarian's rage. That's what they do. That's what distinguishes a barbarian from a really hairy ranger. To me, that's fantastic. I want that differentiation. If I wanted to play point buy systems, I would. There's a ton of really good ones out there.
Niche protection isn't a sacred cow in need of slaughter. It's a core, defining element of D&D. It's the one thing that has never, ever changed throughout all the editions. Each class has unique goodies that no one else gets.
And that's a good thing.