Strictly speaking, yes. Oil degrades over time and, if Mercedes-Benz says your car needs servicing every year, it's not entirely a money-making exercise. Skipping a service might harm its value at resale time, too. That said, it's unlikely that two years between servicing will cause any real damage with the mileage you cover. If it was my car, I'd compromise by paying for an independent garage to carry out a minor service.