Pawns can also change to arbitrary pieces if they reach the end of the board (and I guess a Knight might be the only piece worth changing into other than a queen?)
"Under-promotion" - deliberately not changing a pawn into a queen is very rare and the unique properties of the knight do matter tactically. Under-promotion not to a knight can matter because of stalemate. (Most under-promotion is the domain of chess problems rather than games).
https://www.chess.com/article/view/a-guide-to-underpromotion
I've found bishops to be more useful in end games because they can block whole diagonals and thus I will gladly exchange my knights for the opponent's bishops. Knights can be easily outmanoeuvred - it is easy to render a knight useless for one move and thereby gain some space to turn a check against you into a more favorable position.