Rinsing pasta removes some of its starchines, which gives it a sweeter flavor and a more distinct mouth feel (texture). There is room for both methods in your cooking. Don't limit yourself.
For instance, if you are using the pasta with a starchy sauce, such as a bechemel based sauce, you don't need the added starch of the pasta to get the sauce to adhere. And rinsing the pasta allows its character to present itself on the pallate. In a pasta salad, on the other hand, you might want the starchiness to help hold the dressing to the pasta surface, preventing it from draining away. The same is true when using a tomato-based sauce.
If I'm using pasta in a stir-fry, cornstarch added to the pan liquor will allow a flavor sauce to form that will easily stick to rinsed pasta, and allow the pasta to easily distribute itself in the dish without clumping together.
Think about what you want the pasta to do, how you want it to taste, and what kind of pasta you are using. For bolder pasta flavor, rinse it. If you want a more starchy flavor (and yes, wheat starch does have a flavor), then don't rinse. Will the added starch enhance the meaty flavor of a good beef or chicken broth, or will it distract?
In my home made chicken noodle soup, I want the starch to help add both body and flavor to the broth, along with the collagen extracted previously from the bones. I use freshly made pasta to achieve this, and the noodles stay in the broth.
The key, IMHO, to good cooking, is to forget what your mother, or grandmother, or best freind told you. To be sure, learn what you can from them. But then, open you creativity and do what they told you not to do. You might just stumble onto something that you like better. I know I have, and more times than I can count.
My creativity comes from a knowledge base developed from extensive reading, and a whole lot of experimenting, and fine tuning (almost every night for almost thirty years now, and fequently before then). I tried what my Mom taught me, and took what I liked from her. I did the same with my Dad, my Grandparents, and the authors of "The Joy of Cooking". I learned from them all. And I found that some of what they did was phenominal. And I found that I could dramtically improve on other methods they used. You are the same as me, with the ability to imagine new things, to try them, and make up your own minds.
That's my cooking philosophy, and that's why I teach cooking techniques in my cookbooks, with an emphasis on expanding on what I give you. I certainly am not the greatest cook who ever lived. But I'm a better cook than those who taught me, because I have a passion for it, and have worked with it. And I've put all of that info up in my head, to pull from when needed. And yes, I'm probably sounding very full of myself right now. But I'm really a humble guy who can look at what I can honestly do, as well as at my failures and weaknesses. Don't ask me to teach baseball. But I can help you learn to cook. And the biggest hurdle in cooking is blindingly following something someone else told you.
For isntance, I will never state that any one kind of tomato is the best for tomato sauce, because another variety may just be what's needed to get a desired result for a particular recipe.
The popular San Marzano that is bandied about on this sight may be great for an Italian Red Sauce, but would it work as well in a gazpacho, or for a white chili? Would it have the acidity I'm looking for in my salsa? Or maybe a home-grown brandywine is better for that. I'm growing some yellow tomatoes that I want to try out, see what they are best used for. Only experimentation can give me that knowledge.
I'll get off of my soapbox now.
Seeeeeya; Goodweed of the North