Just because you do not care for a change, or do not understand the reasoning behind the change, it does not mean there is "no reason" or that is it "change for change's sake". That tired old complaint is one of my pet peeves!
I mean, if you don't like that goblins, hobgoblins, and bugbears are now fey instead of humanoids . . . that's cool. Personally, I love it! Whenever the game changes, there will be changes we like and changes we don't.
We have plenty of evil antagonist humanoids, changing goblins to fey brings them more in line with folklore and fantasy literature, and diversifies the cast of D&D creatures. Goblins work better as mischievous dark fey than just another group of humanoids like orcs . . . in my opinion, of course.
And like elves, there is plenty of reasons for goblins to be living both in the feywild and in the material world. Changing goblins to fey opens them up in lore and storytelling potential!
But what if this change messes with my established setting!! So? Easy fix. Keep goblins as humanoids in your campaign. Or tweak the charm person spell to work against humanoid fey under a certain hit die or CR . . . so many simple, easy fixes. And that's what D&D has been about since the 70s . . . taking the established rules and lore and making it your own!