Granted, the "supreme maximum ultimate" goal of Xenoblade Chronicles X is to (technically) defeat every single 90+ enemy you'll find, especially Gradivus and Telethia, who, in my opinion, are the toughest; and in order to do so you'll need every single ability/battle point (hence, arts and skills)/weapon you can, which you can only get by defeating Tyrants, collecting materials and treasures and completing missions. And the most important requirement for those is exploration, lol. 

I don't know, if you know what you are doing there's always something to do and see. 

Dark Souls' world absolutely shits on XCX's, though. Same with Bloodborne. Even the original XBC has a better open world. XCX shares many of the same issues of world that many open world games have. Like thinking open world means outside world only, and virtually nonexistant, very shitty interior level design. It's all overworld. Worse, there's only one very poorly designed hub city. That's it.

The biggest advantage XCX has is scale. It's level design of the overworld isn't even remotely remarkable. It's just landscapes. There is some interesting stuff done with the way the sides of mountains can act as platforms to allow the player to stealth past enemies that out-level them, but that's really it.

That's not to say that it doesn't have a solid overworld, because it does. Comparing it to most other games of it's scale though is really disingenuous, since pretty much all open worlds have shitty level design. It's just not something games are good at as a whole yet. Very few are even mediocre in that regard, and the few that are absolutely obliterate XCX in that regard. Like I said, once the spectacle of the vastness wears off, and it does, all it is an overworld landscape with enemies dropped in as obstacles.

Which is really what the game is all about, especially during post-game. By the time you finish the main story the excitement brought by the landscapes of Noctilum and Sylvalum is over. Is during post game when everything becomes fast travel, fast travel and fast travel, because you must change your focus towards the enemies if you still want to do stuff in X.

It really is: