Deluxe resorts add another layer to my trips now. I'm at a point in my Disney love that it's not all about the parks. I want to relax, take in the details and themeing of the place, and enjoy it on another level then just rushing to Space Mountain. The resorts are probably the reason I come back every year since they're almost a vacation all by themselves. I could spend a week at Animal Kingdom Lodge watching the animals, eating at the restaurants, learning about African culture, talking to the cast members, taking in all the details of the lobby. The Poly, Boardwalk, The Grand... they all help put you in a more "Disney" state of mind. You don't even have to stay at them, but just visiting them makes you feel more immersed. And of course convenience. Walking to World Showcase from the Epcot resorts almost feel like cheating!
I love moderates like Port Orleans and Coronado and they have great themeing. And if it's one of your first trips I think they are perfect resorts. But if you're a seasoned guest who wants a little more than just the parks all day and all night, staying at a place with great dining and drinking, incredible lobbies and decor, and pure convenience... ya gotta do a deluxe.