The argument that casters can often target a defense of their choice is true but of little utility in an actual fight. You can no longer do significant damage in a single attack and you rarely have enough at wills to go after each defense.
Does any class have an at-will for every non-AC defense? Even if one did, you'd have to be human to cover them all, yes.
But, I don't think you need to got that far to hit consistently as a caster. If you have an at-will vs WILL (The Warlock's Eyebite is vs WILL, isn't it?), you're never going to have much trouble hitting. While many monsters have either FORT or REF pretty close to thier AC, very few have equally good WILL. If you cover both FORT and REF, you'll rarely be out of luck, either, as high FORT monsters, like Brutes tend to have poor REF, and high-REF monsters tend to have low FORT. A wizard with Magic Missle and Ray of Frost will generally be in good shape; one with Scorching Burst and Thunderwave just has to worry about not hitting his own party.
Infernal warlocks in particular have two at wills that target Ref.
That's one of the oddities of the Warlock, that only human warlocks have an actual choice when it comes to at-wills. Dire Radiance and Eyebite are probably both more desireable because of thier targetting, since Eldritch Blast already targets REF. But, infernals have plenty going for them in thier own right, not least of which is being able to focus heavily on CON for thier offense (thus also getting more hps and healing surges, as well as a good FORT defense). Star Warlocks have a mix of CON & CHA powers, and thier paragon path favors CHA.
That asside "Infernal Warlocks have trouble hitting with thier at-wills" is a far cry from casters, in general, having trouble hitting.
The higher hit points and general durability of monsters in 4th means consistency is the watch word.
I'm not so sure about that. In 3e, consistency favored the players, because they generally overmatched the monsters in a standard encounter. 4e monsters are often tougher than PCs (until you figure in healing and action points), and pulling out the occassional big hit (Crit, Daily, etc) against them can make a real difference. Even more important is coming up with some teamwork to boost eachother. That potentially benefits anyone or everyone, and can lead to casters as well as melee types hitting a lot more. Melee types get to flank for eachother, for instance, but casters can bestow conditions, or flat-out bonuses.
Weapon wielders attack AC almost exclusively (except rogues who can use precise strike to hit a lot - Weapon vs Reflex + sneak attack = evil damage round after round) so none of the monsters have ACs that are that much above where a PC can hit.
And monsters consistently have non-AC defenses lower than AC. WILL almost always, and either FORT or REF most of the time, too. An encounter power can have a major impact, and a daily can swing a whole encounter - casters have lots of those that target weak defenses. Melee types, not so much.
For wizards this is not the problem it could be. They usually target multiple opponents and the preponderance of rolls means they often hit something.
True enough.
For Warlocks this is pretty crippling. They already have trouble doing the damage of a Rogue or Ranger and missing slightly more often makes it even worse.
Then again, the warlock does more than damage, and his curse does more for him than just the same extra damage as Hunter's Quary, too. All the Warlock at-wills have some advantages, too - Eldritch Blast counts as a basic attack, and all the others have a somewhat defensive aspect, on top of doing damage.
Prime shot is next to useless. In around 20 encounters I have gotten the bonus from it maybe four times. If the defender and warlord are doing their jobs they will almost always be closer to the target then you are.
While it's the defender's job to keep monsters from eating the squishies, strikers do not have to just cower in the back, even if they're primarily ranged like an Archer-ranger or warlock. Strikers are sneaky and mobile as well as hard-hitting. They should often be getting in Prime Shot (or similar bonuses, IIRC, all three have them), in surprise rounds or when slipping past soldiers to attack leader, archer, and controller monsters. Once they've done so, thier usually able to get away again if they need to, also.
'Artillery' is a monster role, a warlock that just stands next to the wizard and shoots is living up to his full potential.
