congratulations to them again, but sure there has to be some land mass somewhere they can use. Or are they just predicting a day they don't want to be bound to any nation?
Elon Musk has tweeted before that many launches will have spent so much fuel that it would be impossible to return to land--necessitating a sea landing for consistency.
The first stage of rockets launched from the US end up over the Atlantic. Unless you want to launch many percentage points more of fuel to propel it farther than it would otherwise go, you're going to have to catch it in the ocean.
The ocean landing is much more technically difficult, but it gives them the ability to use those extra percentage points of fuel on payload.
It's just practicality. Surely they could lease an island or two, they've done it in the past but the barge landing gives opens up much more possibilities.