Well, this isn't true. They completely redid every single character and enemy model. They also redid nearly all of the soundtrack, it was already orchestrated in the original release. There are, of course, gameplay changes and new content added. 

Shinji Mikami apparently stated that remake is 70% different than the original, which has to include the done graphics, cutscenes, audio and all the gameplay changes. Which includes the new areas added, more movement options, gameplay elements and puzzle changes. If that's only "70% remade" then how can you say that WW HD is a complete remake? Especially when apparently, it took them 6 months to develop WW HD, and as far as I know most of textures and characters models are the same as they were in the GC version, but in HD, and the audio too. As for gameplay, except for the Triforce Quest, a few tweaks to items like the Picto Box, new items like the Swift Sail and Tingle Tuner and Hero Mode, what is different?

No joke, someone needs to defend Sony from all the unfair bullying of the interwebz.

This guy gets it:

Significant number of them weren't.

http://forums.zeldaspeedruns.com/index.php?topic=1411.msg25160#msg25160

wind waker HD was $50.

You've obviously not played both and I think it's a good idea for you to stop now.

Guess there could always be a remaster next year.

Really? You want to test that theory? I am honestly shocked by your post.

If you had played the game on Dolphin, you'd know how wrong you are right now.

Character models and the environment geometry (among other things) weren't even retouched. No added polygons. Nothing. Just upscaled to 1080p resolution.

But since you won't bvelieve our words, here is a comprehensive list of graphical differences made to the HD remaster:

http://zeldawiki.org/The_Legend_of_Zelda:_The_Wind_Waker_HD#Graphics

Being a game for the Wii U, The Wind Waker HD runs at 1080p, compared to the original's 480p. The remake uses an enhanced version of the original game's cel-shading, the soft-shading. It utilizes a full-fledged lighting and shadowing system that allows for more realistic and fuller lighting than the original.[6] The remake also features bloom lighting to give a sense of "surreal realism".[7] In low-light areas, the cel-shading gives way to a softer, more realistic shading system. The lighting from torches and other point light sources is now much softer and more realistic, and objects now subtly reflect the color of nearby light sources. Other shaders are used to increase the expressivity of characters. The textures used are the original high-resolution ones created during development of the original game, which used scaled-down versions of the textures to match the GameCube's hardware capabilities. 2D elements such as icons and the HUD are completely redrawn to match the style of the game's promotional artwork.

Heat wave effects in Dragon Roost Cavern now only appear when the fire fountains are spouting. When Link uses a Warp Jar, the transition effect is a shrinking/growing circle instead of the fade-out in the original game.

The shallow water in the boss room for Puppet Ganon, which in the original game did not reflect Link and some other objects, now reflects everything within the room.

Though all other graphical elements were updated for high-definition display, the 3D models and character animations of the original game were left untouched in the remake.

Wind Waker HD is not a remake. It's a remaster just like any other.

By the way, Leadified. IGN, Kotaku, Polygon, Joystiq, Forbes, GameTrailers, Wired, GameSpot, Edge, Giant Bomb, Destructoid, Eurogamer and others all call it a remake.