The pitch of the instrument is more noticed in the warmth of the tone. Not the sharpness. The lower pitches are more resonant and warmer. But competing pipe bands have more challenge tuning together. The lower pitches will highlight tuning errors more readily. So the bands have driven the pitch upwards over the last century.
The "off" I reffered to was introduced by J.S. Bach. Bach was aware of a musical anomaly known as the Pythagorean Comma (or error). It's mathematically/musically involved, but essentially if you try and transpose between different keys, there's this pitch glitch that screws you up.
Bach wanted to write symphonic music for different instruments that played in different keys (hence, had to transpose). So he took the Pythagorean Comma, and divided the amount of the error equally across all the different notes of the keyboard. Each would be ever so slightly off their "pure" pitch, so that instruments tuned to these slightly off pitches could play together and freely transpose. This is what is known as the well-tempered clavier. Well-tempered is the slightly off pitching, and is what we're used to in western music.
Just or perfect-tempering, as in a bagpipe, means the notes are pitched precisely, but can't transpose. This is what gives the phenominal harmonics off the three drones on the bagpipe. Well-tempered instruments can't approach the pure harmonics, and we just aren't used to hearing them.