The necessary and primary job of the head basket is to shield the sensitive, high impedance condenser capsule from electromagnetic interference.
Sources of interference can be AC line hum, AC power transformers or higher frequency EMI from light dimmers or radio transmissions.
A balance between effective EMI shielding and acoustical transparency must be struck. Total shielding of the capsule (by a solid metal cage for example) would effectively block EMI interference but would also prevent sound waves from striking the diaphragm. On the other hand, an unshielded capsule would be very open acoustically, but the mic would not function due to the "swamping" effect of AC line frequency hum which would be louder than the acoustic signal being recorded.