What skills can Evocation replace? It's good for attacks and for some trappings of Might, but that's about it.
Attacks, blocks, and maneuvers of pretty much any type, more reliably than a skill roll. Someone with Guns at 5 could roll a block against a doorway to keep people out, and end up with only a 3-shift block. Someone with Conviction at 5 could block that same doorway with a spell of up to 8 shifts. Evocation can replace a dodge score with something well beyond what the caster might have ever rolled. Though it's risky (or at least, compel-worthy), they can even use it for sprinting. Name a combat action, and there's probably some way to do it with evocation.
As for Thaumaturgy, that's not as broad as you present it as. What you can do with Thaumaturgy and what it takes is largely dependent on GM fiat. Would you let someone use Thaumaturgy to win an argument? To own an airplane? It's up to you. And a teen-level ritual is kind of a big deal, it's not something that you're supposed to toss out casually.
I said versatile, not fast. Yes, it depends on GM fiat, but I'm talking about accomplishing the goal, not necessarily the same effect. Own an airplane? Probably not. Give yourself a speedboost through the Nevernever and make it there faster than any plane? Almost certainly. Create a winning argument? Again, probably a stretch. Putting a solid maneuver on the crowd to make them clap for you even if all you're doing is reading the phone book? Potentially law-breaking, but doable.
If your shield requires even a single boosting maneuver to break, you probably outclass your opponents quite badly.
How do you figure? If your opponent is attacking from 5, that means you're talking a strength of 7 or 8 shifts, which is easy to pull off for a wizard with Conviction at 5 and any focus items.
A zone shield's strength is two less than the power of the spell minus any shifts of duration. And ties go to the attacker, if I recall correctly. Assuming no duration, you need to beat the opponent's attack by 3. If you can do that reliably, why not just take your opponents out?
Maybe you're defensively focused, rather than offensively. Maybe the baddies have a lower attack score than their dodge score. Maybe not getting hit is just plain more important for whatever reason than going on the offensive is.
Worse, it's possible to ignore a block entirely without sacrificing anything. Spending a round maneuvering is often a good idea even when there's no block in the way, the baddies can just do that.
Yeah, but if they have to maneuver to get around your block, that means it's not their choice--you're controlling the flow of battle, not them.
Shields aren't totally useless, but the cases where they are useful are extremely rare.
(Unless you frequently have the chance to prep for combat ahead of time. In that case, shield away.)
They can make a heck of a difference if the wizard's dodge roll is comparatively low (and assuming an optimized wizard in a Submerged game, chances are the dodge roll's not going to be higher than 3), even if it is broken. A monster matching and beating the 5-shift block is going to do less damage than if he'd nailed a solid hit on a 3-shift defense.
Magic is prominent in the setting =/= wizards are the game's protagonists and power players. It's an undeniable fact that Evil Hat intentionally erred on the side of power for wizards, but it seems strange to me that people think they were meant to be the best things in the game.
Maybe it's residual expectations from other RPGs...in D&D, non-casters kinda suck by comparison with full casters. And in some White Wolf games, mortals are by design quite pathetic.
Could be. Also, as noted, the name of the game and its star is a wizard, so those who came into the game from the books are going to look at Harry Dresden, and by extension wizards, as very important.
