Most hardware step sequencers have the ability to determine whether a step sounds, does not sound or is skipped altogether.
As an example, the Doepfer Dark Time has two three way switches per step.
One of those switches has the functions on/off/skip and the other stop/jump/continue.
The first switch controls whether that step is on (sounds), off (no sound/trigger) or is missed out and the sequencer goes directly to the next step without waiting for the clock to advance.
The second switch is used to tell the sequencer to continue to the next step, jump to another location in the sequence or stop.
The switches turn a sequencer from a simple playback device into an instrument in its' own right.
Most hardware sequencers have these functions. The Sonar sequencer's randomise function is useful for adding a bit of variety but does not allow that kind of control.