The problem with Large size is in fact also the space occupied, 10x10 feet means they threaten at least 12 squares as opposed to 8, 32 squares with reach weapons. But that's not counting difficulty with squeezing and other issues from being 10x10 feet.Your size is Medium with regard to your human upper body, such as for size of weapons and armor. But your size is Large with regard to your equine lower body, such as for armor, the amount of space that you occupy, or weight of equipment carried in saddlebags.
Minotaur as sailors is probably based on the Ancient Minoans of Crete.
The Minotaurs were never presented in the Chronicles of Narnia as having any aptitude for sailing.
Gnomes and goblins should be fey.
The planar origins can come with benefits (such as prerequisite for cool magic items) as well as disadvantages (such as target of cool magic items).
Right now I don't see a lot of benefit to the PC. The player is paying an opportunity cost so they can say "my warforged is a construct." That could change if artificers get some kind of "power up construct" spells, clerics get "power up celestial" spells (etc.), or there are some new racial feats (become more celestial/fey/undead/fiend, etc.). I would be good with any of those changes.