Xeno X has a less focused story. But to compensate, it has the best world to explore in a Xenoblade game, four player online co-op (kinda) and a sense of progression that any other Xeno game can only dream with.
It all starts simple: you run very fast, you can jump VERY high and some crazy distances and you take no falling damage. Plus, while you can't climb like in BotW, your vertical walking inclination is ridiculous.
When you mix all of these things together you end up being able to go to a lot of places. I spent literally tens of hours just exploring and trying to reach places by using these very simple tools, but that no other Xeno game has.
But then you get to 20 or so hours into the story and guess what: you get a giant mech that allows you to reach even crazier places (and also inject the combat with some terrific new options).
But... BUT! It's not over. About half way into the story they give you A FLYING MECH. And then... The world is yours. You can go anywhere you want .
This. This progressive access to new ways to discover the world of Mira is what made me fall in love with X. And the best part is that even with just the basic movement options I already felt like I could go anywhere if I tried hard enough.
This seamless world filled with details, enemies, quests, resources and stunning landmarks that I felt I was discovering by myself is something huge to me. It's one of the best open world experiencies I ever had, period. I think the game should get some credit for that...