Why is metal detecting so bad?

Hammered hippie

Many of the people here seem to interpret a vague law very strictly in order to protect archeological objects in their original context. It is very obvious that most of you have never seen or used a metal detector. Any metal detector (bar deep seeking 2 person operated industrial machines) do not detect any deeper than 30cm, honestly.
Nearly all fields in UK and Ireland have recently been ploughed, even grass land. So the top 40-50 cm is disturbed. That is probably why most excavations see the top layer stripped of. So the detecting takes place in a layer that is willingly discarded as being of no interest by most Archeologists.
Since the information fieldwalkers provide is usually welcomed by archeologists I fail to grasp the wrath against metaldetectorists. Provided metaldetectorists steer clear of archeological protected sites and excavations all that can possibly happen is that they provide archeologists with finds that survived the ploughing and possibly point them to interesting sites.Mind you that most of the fields in which metaldetectorists make most of their finds would have gone unnoticed by Archeologists if it had not been for the metaldetectorist finding artefacts in a soil layer that is of no interest to archeologists to start with.
Since archeologists themselves are the judge of what is archeologically of interest and therefore define what is an artefact of archeological value it can be said that every thing found in the top 30cm in a field is intially actually not an archeological find when found, unless decided so later. At least digging around in the top soil can not be regarded as hunting for archeological treasure. Sure, the archeologists themself regard that layer as useless. It could actually be seen as a good thing that metaldetectorist uncover artefacts from that layer before corrosion gets the best of them or the plough utterly destroys them.
Taking all above in consideration one wonders why many archeologists are so agressive in their stance towards metal detectorists that perform their hobby in archeologically unprotected fields. Is it that they have no clue as to what a metaldetector does and how deep it detects or are there other founded reasons to be afraid of the metal detectorist and his beeping ally.
As it seems that many of you in this forum are actually archeologists, or hobby archeologists, can you please tell me what bites you so much about a fieldwalker with a metal detecting device.
Mind you that it is my opinion that whenever something of interest is found it should be sent to the proper authorities. In the UK and the Netherlands this has led to a better understanding and appreciation between archeologists and metal detectorists. Moreover it has led to the discovery of many interesting artefacts (mostly out of context) but also some very interesting sites.