As previously discussed (here), I believe that state trademark registrations have their place in forming a smart trademark protection strategy.
Here’s another reason why they can be useful: enforcing your rights with online portals like Amazon, eBay, and Google. Generally, these providers only act on complaints about counterfeiting or trademark infringement if the complaining party can establish its superior rights by supplying a registration number. At least with Amazon (with whom I’ve recently dealt), this includes state trademark registrations.
Assuming state registrations continue to do the trick (and are similarly acted on by eBay, Google, and other providers), they can be an attractive option for a trademark owner if its goal is to stop online infringement. They’re quick (in Washington, you can get a registration certificate within a week or two), they’re cheap ($105 in filing fees in Washington, including expedited processing), and they’re almost automatically granted.
If you want to maximize your trademark rights, it’s no substitute for a federal registration. But if you only do business locally, or want a quick credential to leverage with online providers, a state registration can be an option to consider.