Sacred artifacts... suddenly I recall the Gorons in OoT talking about the Megaton Hammer as the "Legendary Hammer," and the heroic Goron that used the hammer to defeat Volvagia long ago. Hence the Gorons probably used the Fire Temple as a place of worship, and they placed the hammer so that it...
This may be true, but there are also a few examples of temples being used at least partially for worship. In particular, Kaepora Gaebora in OoT mentions that the Zoras worship the water spirits at the Water Temple. Furthermore, the Earth and Wind Sages in WW pray in their respective temples.