A utility patent gives you the right to prevent others from practicing your invention. This right is extremely valuable. A patent is the only thing that prevents your competitors from immediately copying your invention, taking advantage of your hard work and innovation. If you don't want to be your competitors R&D department, then you need a utility patent.
Utility patents are also critical if you may be infringing on a competitors patent. Having your own patents to assert is often the only way to avoid expensive and potentially ruinous patent litigation.