D&D requires a certain suspension of disbelief. I've yet to see a campaign that had a completely internally consistent setting. This is especially true in settings that seek to mimic the real world- the real world didn't have magic, so you get consistency issues when you mix magic and historical locales. And players are really good in coming up with ways to exploit magic rules to break your gameworld. I don't see a solution for this, frankly, other than 1) players voluntarily not playing the game that way, or 2) retconning really fast to stop players from exploiting things you didn't think up.
I love the comic Knights of the Dinner Table, but if your standard for RPG design is that it must be able to thwart that style player, you're going to hate anything WOTC comes up with. Once you include a certain degree of complex, mundane detail, and then add magical rules that break the rules of mundanity, you're going to end up with exploits. You can either embrace exploit play as a riot (some people love it), or you can voluntarily forgo it, or you can end up in an ever escalating battle between the players and the DM.
I love the comic Knights of the Dinner Table, but if your standard for RPG design is that it must be able to thwart that style player, you're going to hate anything WOTC comes up with. Once you include a certain degree of complex, mundane detail, and then add magical rules that break the rules of mundanity, you're going to end up with exploits. You can either embrace exploit play as a riot (some people love it), or you can voluntarily forgo it, or you can end up in an ever escalating battle between the players and the DM.