One of the problems is that people report windshear when what they really mean is a rapid loss or gain of airspeed due to turbulence, a true windshear event is very rare and should result in a go-around. It would be interesting to know how many events reported by aircraft equipped with reactive windshear alerting (most modern aircraft with IRS systems) have actually set the system off, my guess is almost none of them. If you get a true shear then of course you should report it, you should also go-around if you are anywhere near the ground, landing and then saying we had severe windshear at 300ft is a bit daft really.