Don’t rinse drained pasta unless you plan to use it in a cold pasta salad. The starch that clings to unrinsed hot pasta helps sauce stick to the pasta. In fact, the now-starchy pasta cooking water itself can help marry sauce and pasta more effectively.
Karl S explains how: Before you drain the pasta, scoop out a cupful of its cooking water. Drain the pasta before it’s entirely done, and add it your sauce, along with some of the pasta cooking water, and let the sauce reduce down until it’s at its previous consistency and the pasta is finished cooking. FlavoursGal notes that when you do this, the pasta is actually absorbing some of the sauce as it finishes cooking, making it not just pasta and sauce, but one cohesive dish.
Rinse Pasta after Cooking?