Fetishes by description in the setting of W:TF are actually fairly common -- they are by no means ubiquitous but we can extrapolate from what little text is directly on the topic of these pieces of equipment that they are not exactly legendary, one-of-a-kind magic items. At five dots -- maybe four? -- perhaps but certainly not at one and two (which have fairly minor, utility effects). Also, expect Talens to be adorned all about the place where Uratha have set-up shop or live: "Moon's Allure" (pg. 205) would be exceedingly useful in a bar which werewolves frequent!
Werewolves almost always will attune themselves to a Fetish in order to use it. This means they must find time in the day to wear it for at least one hour. They must also take the time to coax the spirit (more powerful ones are harder and scarier to) into the vessel to enable supernatural effects. Technically, they do not have to attune themselves but then a major benefit of a fetish is that it adapts in form and size to the werewolf making it incredibly useful when shapeshfiting.
Why make one when you can take one? As Cunning is a Renown score, it would be more worth it to trick, charm or outright steal a Fetish from another Uratha. And losing one (especially a strong one) is a sure hit to an Uratha's Glory score. Is it really worth the risk?
Using Essence as an activation shortcut gets expensive for younger Uratha -- this is somewhat mitigated by elder Uratha having bucketloads of it. But then, they'll very likely have other on-going expenses to worry about. Having a font of Essence available to a werewolf is not exactly easy -- the usual suspect, Loci, require constant TLC for industrial application to even be feasible.
Powerful spirits absorbed into fetishes attract attention from the spirit world. A Werewolf that is known for abusing spirits in this way may find their continued efforts to construct more Fetishes are made difficult (the Rite of Contrition is mentioned as an acceptable means of apology). Other, more conservative Uratha may take issue with trying to turn what is supposed to be a sacred, personal ritual into an industrial exercise and it could be argued doing so could constitute Harmony loss at high levels. This is dangerous as Harmony is required for a werewolf to create a fetish in the first place (Harmony - Spirit level; pg. 204)
They must know the Fetish Rite (et al.) in the first place to create them. Many werewolves are far more likely to learn Rituals or Gifts that actually support them day-to-day and at-will rather than an item that's utility is based on having it with them at the exact moment they need it. It will get to the point where the cost of planning involved to do so significantly outweighs the benefits -- it's a bit ridiculous (but there's always one who just HAS to have their Bear's Growl fetish made from a gross, old bear's tounge...) And, of course, Fetish Rite, Bind and Call Jaggling are expensive Rites being 4-dots and two 3-dots, respectively.
Made from crushed flower petals, this powder mitigates the effect that Lunacy has on humans. When the powder is sprinkled on
a human subject, her Willpower is considered to be three dots higher
than normal when exposed to the maddening sight of a werewolf’s
supernatural powers. A cat-spirit empowers this talen. The effect
lasts for the remainder of the scene.