[strager]

A two-byte fixed-point number is likely to be less expensive to deal with than a two-byte floating-point number. (Promotion and demotion cost is pretty high for small floating-point types (bit masking, shifting, oring, etc.) compared to fixed-point promotion and demotion (shift).)

[sdab]

I figured performance came into it also. It would be nice to see some performance numbers though.