Vibrato is a characteristic of flute tone, and styles of vibrato change with general shifts in musical taste. If my ear is drawn directly to vibrato, there is usually some kind of problem: maybe the vibrato is forced (produced with a closed throat) or it is too wide and disturbs the pitch. Tasteful vibrato often depends on the musical result desired, but in general, vibrato is integral to the tone itself. It enhances the beauty of the tone and does not draw attention to itself. Vibrato gives spin, color and motion to the more static notes: i.e, we don't generally vibrate on moving 16th notes. I find a slightly more shallow vibrato that is also a bit slower is useful to aid projection in tutti orchestral passages: a more tightly wound vibrato is less appropriate in this circumstance. And sometimes on big tutti chords, no vibrato is the correct choice.
Think of vibrato as a musical paintbrush and apply different intensities according to the musical demands.