I used to think X2 should have more of a story focus but after thinking on it I'm convinced the opposite would be better. Trying to tell a linear story in an open world setting means your two focuses will work against each other; not to mention giving people expectations that your game won't deliver. X suffered from both of these.
Instead X should have a more Breath of the Wild approach to main story and focus on weaving the worldbuilding/story into the exploration, sidequests, communities, and whatnot instead of having it all in info-dumps, endless cutscenes and on the
back of model kits. The setting in Xeno games is always extremely fleshed out; there's easily an entire game's worth of content if you bother putting it into the game itself. Especially if you start with stuff like "we need to find out more about this planet so we can survive here!" and work your way up to "we need to find clues to uncover the mysteries of this planet" for the end game content.
Leave linear narrative to the numbered games instead of trying to dumb X down into them, is what I'm trying to say. Let each series play to it's own strengths.