Well,
First, you can get a tenting site at the Fort for $42/night (cheapest season 2008 rack rate) and you can get a Value room for $82/night (cheapest season 2008 rack rate). So to start, depends on how you define "comparable" but the Value room starts being twice as much approximately. Oh, you can get an $82 campsite as well but then again you could also staying in a Moderate rather than Value resort.
Second, campers usually have a Coleman stove and a cooler or some other means of eating meals at the site. So by choice they can eat healthier and cheaper. Paper plates and plastic utinsels eliminate most cleanup. The DDP is a waste of money and has as its most attractive asset convenience.
Third, the atmosphere at the Fort is a lot more relaxing. If you go to a theme park every day all day I suppose it doesn't matter. But I also go on vacation to relax. Being cooped up in a Value room would drive me nuts. Sitting out by the pool or in the lobby is too much concrete and glass. Give me shade trees, sidewalks, cool breezes, and friendly neighbors - campers are by nature a more friendly bunch. Ever try to strike up a conversation with the family in the room next door?
Reasons one and two save families BIG money and allows them to come to WDW sooner or more often than the Value/DDP route (special offers not withstanding). For what it costs in tickets this is a big driver for some. I choose the Fort for reason three myself.
I could go on and on. If you feel bringing stuff is a hassle then maybe the Value route is for you.
You won't find a nicer campground than Fort Wilderness!
Hope that was tame enough for you.
Bama ED