Streamlined as in EVERYTHING. Quests, professions, spells, exploring, dungeons, raids. The entire game is streamlined and tells you what to do EVERY STEP OF THE WAY.
It's basically just like playing a single-player RPG instead of being an open world where you need to explore and accomplish tasks to make your character stronger as in a real MMORPG.
"too bad that's not how anyone levels now except for the people actively going out of their way to do so or the ones just clearing zones for quest XP to grind to level 60."
Of course it isn't? That's the whole point, the game is just simply not designed for that anymore whatsoever. Obviously I wouldn't do it myself either in retail, especially considering the massive amount of leveling content you have to pass to get to the current expansion.
And yeah, you're just repeating what I already said. TBC upped the endgame tremendously. The fact that you don't think that the leveling aspect in TBC, which is almost identical to classic instead of more viable classes, is bad is just your personal opinion which the majority of people who like classic/TBC disagree with.
"That's why it had some of the hardest endgame dungeons and two of the most difficult raid tiers in teh game's history lol."
Only thing difficult about WotLK was Ulduar, which I actually liked a lot. But it's nothing compared to Sunwell, vanillaNaxx or even AQ.