Shields stop everything else from impacting your hull: missiles, torpedoes, munitions, lasers. Why don't shields stop hatch-breaker limpets, too?
Well now that you mention it, how do our lasers and munitions get through the our own shields? Are the shields like the airplane propellers on WWI biplanes, connected to our guns via a chain so that our the shields quickly blink off when our bullets pass through? And if so, then I'm a sitting duck when firing my beam weapons for minutes at a time! Very confusing... [wacko]