Calling Xenoblade Definitive Edition a "port" was quite dismissive too, for how much was improved and added to the game. I haven't played many ports with a whole new soundtrack.
That's a stretch, also.
The only thing new is the arrangements. It's the same soundtrack. Gaur Plain is still Gaur Plain; Mechanical Rhythm is still Mechanical Rhythm; Engage the Enemy is still Engage the Enemy. And so on.
From what I heard, they remade the whole soundtrack, and the arrangements don't sound like the originals did. They're new, different versions of the songs. Yeah it's the same songs, but it is a new soundtrack.
Generally with remasters of old games you see that they take the same songs and enhance the sound of the soundfonts so that the midis will sound better, that isn't the case with Xenoblade. Xenoblade already had a fantastic, high-quality soundtrack, and they just went and made another one on top of that, giving you the option to play the game with the original arrangements or the new ones.
As a songwriter myself, I've been rewriting some of my old music recently, making new arrangements of them and all. It's quite a lot of work. For a change as substantial as the one in Xenoblade, it's not too different from writing completely new music as far as the making-of process goes.