The 'is magic mysterious' subthread is getting tiresome.
1) Magic was more mysterious in earlier editions than it is now. There are any number of examples: the potion miscability tables, the fact that duration of spells/potions/effects tended to be random and that the caster would not know necessarily when they would expire, the fact that spells had a chance of failure, the fact that the effect misfired spells were largely the provence of DM fiat, the fact that the DMG contained a goodly portion of the description of many spells kept secret from the caster, the fact that the vast majority of magical items were beyond the players ability to create and those that they could create the mechanisms of the creation were both secret from the players and subject to DM fiat, the fact that Gygax didn't even stat out the artifacts in the DMG lest thier mysteriousness be lost, the fact that spells like identify worked less effectively in earlier editions, the fact that the DMG contained an extensive listing of how spells would function differently in usual settings, the fact that random magic effects and unique items and cursed items played a greater role in the game, the DMG, and in published modules. And so forth. If that isn't enough evidence for you, then there is little point in discussing this with you further.
2) Magic can never be completely mysterious in any game where the players contol it. In fact, its difficult for magic to be completely mysterious in any game where the players know the rules, the setting, and the magic must be described in mechanical terms. In D&D players can become the mysterious figures of power themselves, and they have to have significant knowledge of how 'magic works' in order to play thier characters. Magic in D&D is by default somewhat less mysterious and somewhat more mechanical than it is in some published settings, though not IMO markedly so and a good portion of this is simply the average players greater familiarity with the mechanics. Nonetheless, there is no particular reason why magic need be any more or any less mysterious in D&D than it is in say CoC. There were plenty of 'touch this and suffer some horrible fate with no saving throw' effects in earlier editions of the game. You can argue with a degree of persuasiveness that such gross effects aren't necessarily fun in play, but you can't argue the superiority of 3rd edition in that regard and then at the same time argue that magic in D&D has always been nothing more than a mere predictable commodity. Well you can, but it won't make any sense.
3) The rules of a game contribute to magic's flavor in the setting, but they don't define it. There is nothing about the 1st edition rules that forces magic to be mysterious, and nothing about the 3rd edition rules that forces magic to be a commodity. There is certainly nothing so astounding about the rules that lets someone say, "Based on the rules, you aren't doing it right when you make magic to have this (or that) flavor." There is only flavors of magic which are appropriate or are not appropriate to the setting, and flavors of magic which contribute or detract from the DM's goals for the game. I personally think that you cheat yourself when you make the setting less fantastic than it could be, but there are all sorts of ways to create a fantastic fantasy setting - from the high magic of Arabian Nights to the low magic of a alt-Earth inspired campaign. It's not that one sort of fare is superior to the other, its only that either sort of fare can be prepared in a superior fashion. What is good for one might ruin the other.