Umbran said:
Being aware has nothing to do with it.
The entire history of the game is dependant and devoted to playing the game in ways other than the rules as written. AD&D1e would not exist if people didn't deviate from playing Basic D&D. 3e would not exist if folks didn't deviate from what the 2e books said. 3.5e would not exist if people didn't have problems with what was in the books. White Wolf would not exist if gamers stuck to what D&D did. Etc.
Look at the list of different foums on this site - yes, there is a D&D rules forum. But there's also a house rules forum,which is about playing other than in the way mentioned in the core rules. There's the d20/OGL forum, again about playing the game other than in the way the D&D rulebooks are written. The General forum, too, depends upon the existance of other ways to play. This very discussion is based on the idea that gamers already have relaized that there's more than one type of game you can play by the core rules. People are questioning the way the books say to play the game all the bloody time! Constantly. Insessantly.
You keep saying you have this fear - buy you have produced no evidence that it has ground in which to root. The history of the game up to this very day almost literally screams at you that gamers do not, in general, stick to what the rulebooks say. They play in the way that they have fun.
Stop blaming subtle book-induced hypnosis for what is simply the way some folks like to play.
Manipulation of the sort you suggest does not function when the intended victim has lots of time to think and full information at their disposal. The full information is right there in the rulebooks. Time we have aplenty. There is no reason to believe that gamers are somehow manipulated into behaving in one way and only one way and never should they deviate.
So the fact that MtG always comes out with new rules has no effect on those who play casually, have time to think about there deck builds, and do not play in tournaments

?
I see things a little differently (again, milage may vary). New cards meant a spending frenzy to create the best deck, since new changes either nullified certain strategies or introduced new ones, even if you concider MtG houserules used on site (we did have a few).
I have seen the same situation in D&D, and in the same in forums of play (school, campaign groups, etc). Yes, everyone is a casual player, but a DM cannot control what their players will purchase. These players are going to buy these optional rules, see new improvemenets, options, or rules changes (the improved critical feat rules change from 3.0 to 3.5 is a good example), and want to run with the new rules (I've seen several 3.5 OGL sources that "allow" Improved Critical to stack with similar effects, per 3.0. Players don't have to argue about using 3.0 rules in a 3.5 game anymore. They just quote a new 3.5 source). The DM now has to decide whether this rule or that applies.
To be honest, I have yet to meet a DM has played a 3.0 or 3.5 game straight from the core rules. It can be done, but most players don't want that. As you said, players deviate from the original rules. If you enforce a strict 'core rules only' set, you lose players. This happens (or happened to me) even if the group agrees on this ahead of time. The new 'options' are just too enticing. Everyone will want to play their own style, and a DM will have to make allowances.
Also, the 3.x rules also follow the MtG philosophy (sorry if I butchered the spelling) of 'a rule for everything' instead of 'DM's call', as mentioned earlier on this post. Yes, the rules say that DM's have final say, but human nature prevails is this case. I've run into several players who site obscure new optional rules, even when the DM has already made a call on a situation previously in the campaign. And these weren't the rule lawyers of my group!!
My point is that I see so much out there that the DM has to make a call on, or explain to his players (ever have to tell some one that the NPC is not targeted by AoO's for a reason, and not explain why? Or better yet, have that player mimic the same strategy because the rules now allow it?) even with the rules as they are.
I'd say that the min/max folks have enough to play with for now, let the roleplayers have their fun...