I certainly didn't dislike TLJ (and I did very much dislike Dreamfall), but I don't think it is in the same league as classic adventures. The fundamental design is not good. The puzzles are not good, and the pacing of puzzle-solving and exploration is quite bad, skewed heavily toward ping-ponging from lock to key back to lock. The puzzles are often not well contextualized -- a point that needs a little elaboration.
Solving the puzzles generally does not develop April's character -- by this I mean, the way she solves puzzles is not indicative of character traits (compare SQ, PQ, Loom, Full Throttle, QFG, Gabriel Knight, etc.). The test here is, write the following sentence, "Because April Ryan is [X], she solves this puzzle by doing [Y]." That sentence is often coherent for the games above ("Because Roger is a bumbling janitor," "Because Sonny is a by-the-books cop," "Because Bobbin is a naive Weaver," "Because Ben is a bad-ass biker," etc.). It is not often coherent for April, in part because I have no idea what [X] should be ("a bougie art student"?), in part because there is no [X] that works for the kind of puzzles she does, other than "a bumbling janitor" or "tinkering scavenger," which she obviously is not. The incoherence of the puzzles is one reason I don't know what [X] is. The game never teaches us April's character through the gameplay. It tells us things about her through exposition, but those are largely unrelated to the gameplay.
And the nature of the puzzles also generally does not develop the setting. This is particularly true of Stark, where the puzzles are sometimes at odds with what the setting is supposed to be. (One that I recall is the gasoline powered heater, a technology that makes no sense at all in the setting.) The best adventure games use puzzles to bring the setting to life. Gabriel Knight (which I think has its flaws) does this pretty well. Loom does it exceptionally well. And King's Quest, for all its foibles, uses the puzzles very cleverly to embody the norms of fairy tales. By contrast, adventuring in Stark does not feel like a dystopian science fictional adventure, and adventuring in Arcadia doesn't feel like a fantasy epic. I don't mean watching the story. Watching the story is fine in these regards. I mean playing it. The obstacles April is overcoming, and how she's overcoming them, don't embody the feel of those settings -- compare Indiana Jones, The Dig, QFG, etc.
In addition to these flaws with the puzzles, TLJ's dialogues are much too long. The long dialogues are part of the game's appeal, of course, because they allow TLJ to present itself as having a richer setting, a more nuanced story, and more developed characters than other adventure games have. Maybe it does, maybe it doesn't. But the dialogues in TLJ are little different from the audio cassette that came with Loom -- you sit back and listen to what amounts to window dressing. They aren't gameplay (there is never a wrong options, and you almost always have to go through every option to proceed) any more than wiki browsing is gameplay. You generally aren't expected to retain, digest, and employ the things characters tell you to solve puzzles. In other words, there is a cartoon you're watching in parallel with a game you're playing. The cartoon is fine as far as it goes, but it prevents the game from ever having a proper adventuring flow IMO. [EDIT: To some extent, this attack is valid against Primordia and Strangeland, too. But (1) I've tried to keep the dialogues much shorter than TLJ's for that reason and (2) you often do learn things in dialogues that are necessary to solving puzzles. Also, I'd be the last person to say that I can design games at a level with the classics.]
Finally, on the story itself, I think the charge that it is merely teenage pap is probably too harsh, but I think the suggestion that the story seemed good because of when the game came out is fair. When TLJ was released: (1) there was a fairly limited supply of multimedia, serious fantasy/scifi story-telling produced for a domestic English-speaking audience* and (2) adventure games generally had silly stories. So an adventure game that was basically an animated Piers Anthony novel (the specific Anthony series being duped is Split Infinity) with a serious Melrose Place kind of story-telling satisfied a need that other games weren't reaching. Moreover, TLJ looked very beautiful at the time (and still looks pretty nice!). Nowadays, most adventure games have serious stories about troubled women, and multimedia, serious fantasy/scifi is like 90% of large budget productions across all media. TLJ wouldn't stand out today, and I doubt it would be remembered as a classic.
(* Yes, yes, I know Ragnar is not from an Anglophone country. Still -- Dreamfall is very much "domestic" compared to localized anime.)
To me, TLJ belongs in the camp of "very pleasantly remembered adventures than weren't Lucas, Sierra, or Revolution" -- games like Kyrandia 2, Dragonsphere, Rise of the Dragon, etc. I don't see any reason to crusade against it, but I do sometimes feel obliged to hold the line against its being considered a classic.
In terms of politics, I don't think the criticism is apt. Dreamfall is goofily heavy handed and tries to address current events and specific trending issues (i.e., events current to the game's release). TLJ has lots of political messaging, but it's the kind of messaging that is basically generic and akin to what you'd find in Lord of the Rings (big corporations bad, environment good, different sorts of people can band together to fight oppression, etc.). The college kids seem like college kids ought to.