As I have read a few books, such as Sir James Frazier's The Golden Bough that deal with what might be termed "magical practices" in various societies -- from crop planting and harvest rituals to trying to keep Death at bay --, I think we need to ask what is magic used for in a game.
In pre-modern technological societies, such as those that prevailed around the world only a few centuries ago, many cultures had rituals to address various facets of life. Generally, these rituals were seen as effective -- and only failed when something was either wrong with how the ritual was performed or wrong with the community. Thus, such rituals were generally seen as reliable -- barring unforseen circumstances.
Thus, magic can be seen as serving the same purpose as technology: a way to accomplish something desired by an individual or a group of individuals. Mind you, magic as presented in traditional societies, fiction, and RPGs has some commonalities with technology. Both have experts and many common people don't quite understand how everything works.
As for the issue of keeping magic feeling "mysterious", I think you can do this with any rules systems. As I recall, Dragon Magazine Issue 200 had a GREAT article on this (I have it at home, and will try to reference it later.) One thing that you can do is to introduce new spell effects, or try to personalize things for a given order of wizards, a specific sorceror, or a religious sect. For example, maybe priests of the Egyprian god Ra cast spells that display light in addition to whatever else they do. ("As Pa-Ser, priest of Ra, touched the sword wound, light welled from his hands pouring into the deadly cut as it closed.") Or a group of fire elementalists may cast a magic missile spell that shoots out what appears to be tiny flames. It is up to a DM to provide balance and flavor to his games.