"I didn't say either of these."
Never said you did; but unlike us normal pukes; you are above simple name calling.
"If you have the prescience to cast it. In pen and paper games, the number of times I've seen wizards/sorcerers get off a shield spell when they need it has been low -- whether they were enemies or PCs. The spell only lasts a minute a level, so a caster is almost never just "walking around" with it up. If a wizard puts it up, opposing casters often detect that it was cast and either a) target others with their magic missiles b) target the caster with other spells or c) cast from the direction opposite their shield."
All true; but it still useful to have as since a magic missle spell is more dnagerous to a mage in a party than it is to a warrior. The fact you got the opposing mage to change targets is already a good thing. And, that's if he passes the spellcraft check to detemrine which spell is being cast (more than likely for any wizard worth his beans; but not an absolute given). And, like I said, there are tons of other ways to deal with magic missle. Shield is just the easiest and most absic way since it's also a 1st level spell. Remember, that unlike PC d&D games, your typical pnp D&D game is not going to have lots of battles during one day unless the campaign s REALLY, REALLY combat heavy so not being able to cast your sheild spell as soon as you wake up isn't too bad anyways.
"Mana is about having a common pool of energy from which a variety of effects are drawn. Specific implementations of mana systems don't discredit the type of system itself."
Maybe. But, everything cna look good in theory; but in practice I have yet to see personally a mana magic system that gives the versality that people brag about and still keep the spam a spell under complete control. Until then, I'll contninue to have my doubts when hearing people praise it.
"lot of times, the challenges of an adventure are unknown until they are encountered. That's why it's an "adventure" and not a plodding path through predictable encounters. A D&D wizard can plan for encounters for hours and still be caught completely unprepared by what awaits him or her in the session."
True, and false. Sure, adventiures are often unpreditcable. Afterall, in theory, that's what makes them most interesting. Of course, that's why scroll creation was invented by some know it all wizard all those eons ago. Scroll crafting is rather cheap (too cheap almost, imo) so you can use that to make sure you have at least a few copies of those odd spells that rarely come into play but when they do are very useful ( water breathing one example of this), and a few extra combat spells just in case you do run out of your spells.
"The system mechanics fit how the designers built the cosmology of the D&D universe. Not exactly an awesome or even difficult task."
Maybe so; but it is still very logical; and still gives a wizard (and other casters) a lot of freedom to play their character as they see fit without completely free reign to spam spells like mana systems do.