Why should anyone use a laminar flow system ?

The Basic reason, of course, is to make available source of air from which most of the particulate matter has been removed, as a matter of fact 99.99% of everything air-borne down to 0.3 microns should be screened out. Now you have an environment whose air supply is free of bacteria, fungi, pollen, and practically all air-borne dirt, to use for whatever purpose such an environment will do the most good.