Well, it is usually very easy to come up with some method to derive the (well-known) piece values for orthodox Chess from the move counts by some calculation. After all, there are only 4 piece types. More often than not these would give totally wrong values for unorthodox pieces.
In this case you don't even manage to reproduce the correct values for the 4 orthodox pieces: it is well-known that a Queen is worth between 1 and 2 Pawns more than a Rook and a Knight, while your method results in the Queen being exactly equal to Rook + Knight.
Well, it is usually very easy to come up with some method to derive the (well-known) piece values for orthodox Chess from the move counts by some calculation. After all, there are only 4 piece types. More often than not these would give totally wrong values for unorthodox pieces.
In this case you don't even manage to reproduce the correct values for the 4 orthodox pieces: it is well-known that a Queen is worth between 1 and 2 Pawns more than a Rook and a Knight, while your method results in the Queen being exactly equal to Rook + Knight.