[ctdonath]

Were redundant choices culled? No point in tracking all variations of pawn > queen/rook/bishop when one includes the moves of the others.

[tromp]

There is sometimes a point when you need to avoid giving stalement, like in the famous Savedraa study [1] or the vastly more intricate Babson task [2].

[1] https://en.wikipedia.org/wiki/Saavedra_position

[2] https://en.wikipedia.org/wiki/Babson_task

[CrazyStat]

Sometimes the queen having both rook and bishop moves is a liability. There are positions (real positions from real games, not merely hypothetical ones) where promoting to a queen results in immediate stalemate, while promoting to a rook wins the game.

So those choices are not redundant.