I played from the very day of release, and the quests added during the Vanilla days were mostly high-end zone (like Sillithus ; there was maybe also Dustwallow Marsh, I honestly can't remember if it was during Vanilla or after, but in all cases it was pretty late and I had already leveled three or four characters by then, so my point stands), so no it doesn't change. There was always, always, more then enough quests available. Always.
The only thing is that you needed to switch zones, but that was by design.
When playing my main, I even wanted to maximize the amount of discovery of the game I could, so I purposedly avoided rested XP by disconnecting outside inns. I still managed to reach 60 with some zones mostly untouched.
You'll notice I already pointed at this :Personally I was super casual and spent more of vanilla leveling and never ran into this (I also hated questing and mostly leveled via dungeons), but I definitely remember in early vanilla people saying that there isn't enough quests for some level ranges. I also remember from early leveling guides that at some level ranges the optimal strategy was to just grind mobs.
or dumbasses who just followed a guide which told them it was "more efficient" to grind for level X, and they followed like sheeps rather than explore and discover that there was, in fact, tons of quests - but it required to change zones.
People saying there wasn't enough quests for level ranges were either the guys who blindly followed the guides, or just fucking idiots who didn't bother to get out of the zone they were in.
I agree with everything, save for the bit where you say it's fine to have level range without quests. It's fine if, like in Vanilla, you have to go elsewhere to find them (they were even nice enough to put breadcrumb quests everywhere to lead you where you might need it), but I don't agree that an actual lack of quests would be acceptable.Personally I think it's perfectly fine to not have an uninterrupted chain of quests through all the content. The current model feels like a brainless autopilot on-the-rails experience where you cannot fail and you have no choices to make. I much prefer a model where I'm put into a world and have to actual figure things out for myself, where I can actually fail or get stuck, and where at different points I have to do different things. To me it's perfectly fine to have level ranges without quests, where you have to grind or run dungeons.