The thing is, there's lots of interesting fantasy out there, in a variety of mediums. A lot of it, however, is set in fairly ordinary, medieval (and Tolkien) influenced worlds. That's fine, of course, to an extent. Tolkien is my all time favourite writer, and I love Middle-earth, but when watching many modern movies and playing modern video games, I find myself yearning for something more. Where is the imagination? Where is the exotic? Where are the, well, Pandoras? If you took the aesthetic vision of Avatar, and combined it with perhaps a slightly less cliched plot, you could have something truly wonderful. And that is, of course, only one possible world out of an endless number that could exist if imagination was the only limit.
In movies there is of course the question of expense. A medieval fantasy is obviously easier and cheaper to create than a glowing jungle filled with imaginative creatures. But in video games this should be less of a problem. Games like The Elder Scrolls series are bringing whole fantasy worlds alive, so why not let the imagination really soar while you're at it? Japanese games traditionally have been a little better in this respect, but there have been few really great titles in that scene in recent years.
When I'm designing my own worlds, for my role-playing games etc., I strive to make them in some way imaginative and exotic, even when borrowing elements from a variety of sources. Regretfully, I'm not at all gifted in visual arts, nor am I even particularly good at describing things verbally. The ability to sketch creations would certainly be helpful, both in the design stage and when sharing these creations with others.