I'm not a vegan but I eat eggplant parm and other veg dishes. Some of these dishes are quite tasty and I actually prefer to meat dishes sometimes. Chicken is probably the most bland meat there is and I generally avoid it when dining out.
Thus why the chicken is dressed up.
And if prepared correctly, and, most importantly, cooked correctly, that chicken will be tender and very moist. Take that along with plenty of cheese, and a fair helping of tomato sauce and spaghetti noodles, and you've got a great amount of flavor. Only boring chicken is bland, season it up before throwing it in a dish, and cook it properly.
Chicken is great protein to put into just about any flavor of dish, it'll only complement and mostly be hidden by the other flavors. Win-win in my book.
The only thing that beats that when it comes to those ingredients, is my hamburger and sausage slow-cook spaghetti, with a dash of cabernet in for good measure. Mmmm, so delicious.