"I guess the place has been around for so long it has had time to be treated in lots of different ways."

Right my theory, think of cantons and tribal centres, we have Avebury, Stonehenge and the area around Carn Meini and others in the south west. Long term settlement at these places require stone, Avebury had lots but not so Stonehenge - it had to be imported from elsewhere. So when we 'read' prehistory it should not always be through the lense of ritual and religion. Water and stone come under practical, that stone could have held a 'sacred significance' is probable, that it could also have had a creative aspect to it, either for tools, for colour, or for shaping into megaliths or crafted into longbarrows - shows that it is multi-functional, so why does a few chips have to be seen as 'religious', when stone dressing is very apparent at Stonehenge - chippings after all will fall quite happily through gravity to the ground...
I blame the media for all this ;) take one completely daft concept of Lourdes, plant it in the mind of the public, and we're off....