I do late 16th century reenactment, including pike drill and demonstrations. We all have swords, but the only way to use them is for everyone to drop the 5 meter long pole and draw swords. And you really really don’t want to be armed with only a sword on a battlefield.

The alternative is either wheeling around (the turning circle of a unit of pikemen is horrendous), or raising the pike straight up and reforming into a square, and those aren’t exactly snap maneuvers.

And the guys pictured here have at least an extra meter of pike to deal with, and a shield too.