The non-castling variant was invented by Vladimir Kramnik[2] explored by Deep Mind not on a whim but specifically as part of Vlad's exploration of whether this chess variant would help to revitalise the game given how computer evaluation has affected theory.[3] There were also a couple of no-castling tournaments played, but like chess960[4], opinions were very much divided about whether or not it was actually any kind of improvement.
[1] Even though I pretty much always fall into stalemate traps in blitz.
[2] Former world champion and lately old guy shouting at clouds about cheating
[3] https://www.chess.com/article/view/no-castling-chess-kramnik...