What is the benefit of a trademark?
Trademarks may be offensively used your trademark offensively by prosecuting third parties using an identical or similar mark. With regard to a defensive use, the trademark registration provides protection against third parties who intend to dispute the use of a mark or name.
Doesn't the right to a name or company name provide enough protection?
The big advantage of a trademark is that, as a rule, its geographical designation outreaches the designations of a name or company name respectively. For a trademark you may easily obtain international protection by registration, if necessary worldwide.