The caramelization that occurs when you roast tomatoes in the oven is an essential component of any tomato soup, which is why so many recipes require it.
Olive oil and salt will intensify the tomatoes' flavor, while the sugars that are formed in the cooking process help add a touch of smokiness and more depth.
One great herb combination you're likely familiar with is a pizza spice blend, which contains oregano, dried basil, or Italian seasoning. You can also go a Southwestern route.
Steer clear of reactive cookware and stick with the non-reactive kind. Reactive cookware, such as cast iron, is free of enamel and other protective coatings.
This can lead some of the metals contained within to leech into the food. Tomatoes, being especially acidic, tend to draw out those metals more than other types of ingredients.
Reduced cream will be thicker and less watery, and the moisture will mostly evaporate. In turn, this gives the soup a creamier texture without overcooking the soup itself.