It is true that you can legally protect a trademark the moment you start using it. So why go for the extra effort to get a federal registration? Here are a few reasons:
1. Increased Certainty. Once registered, you can be relatively certain that you actually have a trademark. If you are relying on common law rights only, you may not actually have something that can be protected. It may be too generic, or already in use or have a number of other problems that will prevent you from actually enforcing it.
2. Automatic protection in all 50 states. If you don’t register, you only have a trademark in the areas you are using it. If you are in Minnesota and only sell in the upper Midwest, you may not be able to stop a competitor in California.
3. Customs enforcement. Once registered, you can record your trademark with US Customs who can monitor imports for infringing goods.
4. Monetary damages. Though they are not frequently awarded, it is possible to get damages based on the profits made by infringing goods.
5. It puts others on notice. Records at the U.S Patent & Trademark Office are public. Courts will assume that anyone using a similar name had known or should have known about your trademark.
6. You can more easily stop cybersquatters. If a domain name is registered that is infringing your name, one of the things you will have to establish is that you have trademark rights. Registration is not required, but it will be much more difficult to either in arbitration or in court without one. Same goes for search keywords, adwords, etc.
7. You have an asset to borrow against. Nearly every business needs to borrow money at some time. It is easier to do so if you have assets to use as collateral. A bank can much more easily obtain a security interest in a registered trademark.
8. ®espect. This one is a bit vague, but a company that knows and uses its legal rights signals to the world that it should be taken seriously. Trademark registration is one small piece of that, but its an important one.