. . . since you probably came to the wrong place looking for a debate on this question.
While it's true that some people could visit WDW again and again without getting bored, you also have to consider the opportunity costs. Unless you are independently wealthy and do not work for a living, you have limits to your available vacation money, your free time, or both.
It's a great big world, and there are countless places to go and things to do. If you have limited time and/or money, every repeat vacation at WDW is a missed opportunity to see some other interesting and fun part of Planet Earth. (And don't fool yourself into thinking that you're seeing the world by walking around Epcot; anyone who's ever been to those countries will tell you Epcot resembles foreign countries the way Splash Mountain resembles the Everglades.) Those experiences are especially valuable to children, who are still forming their views on the world and benefit from the widest possible exposure.
Moreover, WDW is so expensive that a week there would cost as much as several weeks at other vacation or travel destinations. So the lost free time is the same, but you are missing more than one opportunity by going back to WDW. (And that doesn't even address the issue of spending money on vacations that should be spent on more important things, such as college or dental work.)
Now, having said that, I think repeat trips to WDW over other completely fake experiences (i.e., cruises or all-inclusive resorts) are acceptable. If all you want from your vacation is to forget that there is such a thing as the real world, then WDW is a terrific place to do it. (Or, more accurately, Orlando is a great place to do it.) But if your spouse doesn't want to miss the chance to see the spectacular natural beauty, facinating cultures, and living history that the world has to offer for another trip to WDW, he has a point.
As middle- or upper-class Americans, we are incredibly lucky to have the opportunity to travel on leisure time at all, but that good fortune has limits -- the ultimate limit being our short lives. As great as WDW is, it would be an utter shame to squander that good fortune and precious time in the same little place again and again and again and again.