Is it so surprising ?
Black has a tremendous positional advantage, so there
must be something around the corner...
And that leads us to the solution, Alex:
It is all hidden "behind the (double) corner".
No wonder
you liked it a lot !
You have to invest further material to promote at the square where the king has least mobility.
Isn't that showing that mobility is not everything in the game of checkers ?
Sometimes to have targets is even more important.
And by sacrifizing his free pawn black gets more then one target.
To me it is more surprising, or shall I say : disappointing, that white still has a draw

(
Maybe we should give a win
on points to those who sacrifice but only get a draw, just to boost beauty and romance in this game

Greetinx from hot, but stormy Europe,
Ingo