If your goal is to cook your chicken relatively quickly, the only reason to keep it whole is for presentation/appearance and to avoid cutting it up. (For example, I know some people who simply hate handling raw meat, and I imagine for them that the task of butterflying is not only laborious but distressing.) From my perspective, you can save so much roasting time by investing a couple minutes in cutting it up -- and it really only takes a couple minutes once you know how -- and get better evenness and get better crispness. Why not butterfly or cut directly into quarters or pieces?
However, sometimes the goal is not saving the greatest amount of time. The question mentions aromatics and elements placed inside the cavity: those will have greater impact when roasting for a longer time at lower heat. But the even greater advantages for the whole bird come when you lower the temp even more and take a "low and slow" approach, as some people do. While the USDA doesn't approve this, many people roast their chickens (and other birds) at 250F or 225F or even 200F, for anywhere from a few hours to 8 hours or more. With extended roasting time, the meat and connective tissue softens, the fat renders beautifully, and you get an extremely tender and succulent texture, while any aromatics have time to be absorbed more fully.
If you cut up your chicken into parts or butterflied it before such a long roast, it could dry out, and you wouldn't have the moderating influence of the large structure to keep the interior relatively balanced. It's like the difference between cooking a steak and large roast of beef. Use the same logic for large hunks of poultry: If cooking fast and quick, cut up is better. If cooking low and slow, there are flavor, texture, and moisture benefits to keeping it whole.