Why you need IS ...

Using flash inside a (fine dining) resto is distracting to other customers.
Going lower than 1/60 shutter speed even at wide angle will result in blurred photos.

The following shots are captured with IS enabled.

1/30 shutter speed

1/15 shutter speed!

1/15 shutter speed!

1/25 shutter speed

1/15 shutter speed

This is a low 1/6 shutter speed!!!

Why you need wide angle.
Step back a little and people starts walkin' between you and the subject!