That's because Kevlar is the only stop in town for armor against modern weapons; which are all basically just guns. If there were qualitatively distinct armor options (say magnetic/energy armor vs physical) or if other weapons were more common (say Flamethrowers) then the arguments might be comparable.
Sure we do. We can equip police with leather jackets, steel breastplates, shields, helmets, and all sorts of things. We do not because these items are either rarely useful or suffer major liabilities. For a similar reasons, I would not see wardens being routinely equipped with anti-ghost charms, mind shields, salve to see through fey illusions or any number of specialized defenses or attacks. But common attacks – especially non-magical attacks - or common tools are something that can be easily incorporated. That is why cops are often issued batans. Not because they are the primary weapon, but because it is a simple tool that is often useful. That is the type of magical equipment I expected the council to issue.
But who's to say that Harry's brand of Shield that is a force-wall is universally superior enough to Carlos' Entropy-based shield to the point where all wardens should standardize to that method. His Duster has been pounded through an awful lot.
I suggested general purpose items that provide passive defense or some other useful non-combat function make a lot of sense. Foci of any sort are very specific to the mage and it would be tough to make one for another that would be super efficient. Harry might be able to use Eb’s staff as Eb trained him, but not as effectively as his own staff. Using the Merlin’s staff would be even less effective. The point of issued equipment is that it works no matter the specific strengths of the wizard vs common threats/use cases. It is a supplement, not a replacement for the wizards magical abilities.
There is also the matter of the Burden of Upkeep. Per WOJ the vast majority of Harry's time goes to basic maintenance on each of his gizmos, or they eventually get worn down by the sunrises and need to be re-enchanted. Each item that is Standard Issue is one more timesink for each warden, translating to one less item of personal/optomized usage they can maintain themselves, or less time they can actually be doing the Job of a Warden.
Upkeep is the cost of all magic items. It does not matter who creates. Upkeep certainly limits how many items a wizard can have, but making sure wardens have a small number of very well made general purpose items can easily save lives – and the warden can keep the maintenance going. And if the warden does not want it, he can give it back. Very experienced wardens probably have only their own self created gear, but younger wardens would really benefit from issued gear.
And to point to a specific example, Thorned Namsiel was able to go right through Harry's shield using variances in magical "frequency" (in SmF).
And I think that Kevlar vest will do diddly against a marine sniper rifle. That is not an argument against wearing Kevlar as very few people pack marine sniper rifles. Denarians are major league threats and few wardens would be easy going against any one of them. Even if they did, the general purpose defense provided by the council would be only one of their defenses – and not the most important one.
Standard equipment is a supplement that provides a minimum baseline of capability. It is not a replacement for what the wizard can do and would never be the primary element in a wizard’s arsenal. But this solid baseline can often make the difference between success and death/serious injury fro common situations. Equally important (not just defense), common equipment can allow wardens to more easily work together, communicate, or effectively deal with issues outside their personal strengths.
I'm not sure I agree with this statement. The main purpose of the wardens isn't to fight wars against other Accord nations: it's to police against warlocks who break the 7 Laws.
The White Council has had multiple wars and conflicts with other supernatural powers --- in the books we have seen them go to town against Formor, Rakashashas, references to several vampire wars, and vague references that indicate that wars are not uncommon among the supernatural set. And all these bad guys use various non-magical threats along with any magic they can do. The reality is that the wardens have probably been in many small conflicts, minor wars and several major wars in the last century or two. They may exist to enforce the laws, but they are also a military force and are routinely expected to fight as such.