The Tangent Ripple is a competent, entry-level tool for anyone who takes color seriously, but who doesn’t want to spend over a thousand dollars on an input device.
Like anything else, when doing repetitive work where time is money, professionals need every tool they can get their hands on to work faster. Using an input device like the Ripple allows you to manipulate multiple parameters simultaneously. For example, you could add blue to the shadows while you boost red in the highlights. If you can reduce the amount of time spent per shot by 10 seconds and you have 1,500 shots to correct — well, it adds up.