If Torna is not a stand alone prequel game, what can I walk into walmart and buy a physical copy, and play it without the need of to own or play Xenoblade 2?
DLC is content added to a game, Torna is its own game with its own 30-40 hour length.
Your Link's Awakening logic is fine as long as you look at Miles Morales and Demon Souls as DLC and a remaster as well. (you probably do though, which is fine).
Your preference of WiiU ports is your opinion. I enjoyed the new content more and I did not even have a WiiU for games outside of the Zelda ports, so we will have to agree to disagree here. You have every right to that stance, it is the people who never even owned a WiiU or Switch saying it that comes off as reaching downplay.
You 100%ed Torna in 30 hours? That's way too long, I'd say.
Too long in what way? If you think 30 hours is a long game, I assume you must not play JRPGs in general.
But if you mean to say that you think I spent too much time in the game...
As you can see it lines up with what is expected from Torna. Hell the main story alone clocks in at 17 hours if you ignore as much side content as possible.