It's also the less stylized art of late 1e and 2e. You can potentially do art in the style of Otus purely working with what is in your head. It you want to have the realism of Elmore, you probably need a model to pose for you. Good models cost money, fearsomepirate already mentioned.
As someone that hires art models on a weekly basis, being a good art model isn't as much about being good-looking as it is about being able to come up with dynamic poses. That's a real talent. It's why the model-dependent work of Elmore involves so many people blandly standing still.
I think Jeff Easley finds a great sweet spot in the middle. His paintings are highly active and very detailed in their rendering. That's really not easy to do, especially when working on the timetable of a professional illustrator.