The Spanish sword-and-buckler men were used as a support troop for the Spanish pikemen though. Others used Doppelsoldners with halberds and two-handed swords for the same purpose - hacking a breach in the enemy pike block to break the deadlock of the "push of pike".
And fortress assault and suchlike where pikes weren't of much use, of course.

Helmet and cuirass were pretty much the minimum required armour, and more was heartily recommended.

Also, at least once dismounted Burgundian knights wielding their heavy lances as spears gave Swiss pikemen serious trouble from the front; they got later hit in the flank by the halberdiers (who still by that point formed a distinct unit) and rolled up though.