Putting aside, for a moment, the financial component and what people do to pay (or put off paying) for their WDW vacation, going to Disney became a few-times a year thing for many people because WDW keeps expanding and offering more services, building more resorts with more amenities, more parks or attractions within existing parks, not to mention maybe some of the things you can experience...outside of WDW (shhhhh! Pretend I didn't say that!)
In a way, Disney had become the 21st centuryt equivalent of a Catskills vacation, or a Jersey Shore/California Coast vacation. These locations still have their allure and their fans, but in the P.W. years (pre-WDW) they were much more popular locations, and it was common for some families to spend entire summers in these locations, perhaps with the major breadwinner continuing to work from Monday or Tuesday to Thursday or Friday and driving/flying down for 3-4 day weekends with the rest of the family. And while it's discussed more as a hypothetical than an actual experience, it's true that you can actually go to a WDW resort, enjoy all the bells and whistles of that resort (and all the other resorts if you choose to visit them) and have a relaxing, restful vacation without ever stepping foot in one of the parks. Of course, the argument is then, you can do all those regular vacation places for less in any other regular vacation destination. But a WDW does give you the luxury/option of both. If one parent and/or child in a family thinks he/she/they are beyond theme parks, or just want to rest, they can lounge poolside and do spa treatments or ride bikes or boats or enjoy campfires blah blah blah, while the rest of the family spends a day on sensory overload. Everybody gets to do what they want to do. It's kinda why WDW expanded as it did, recognizing that the theme parks is the coffee, and some people like their coffee black, but the resorts and all their amenities are the creamers that other people can't have their coffee without.
As other people have said, nobody should take out a mortgage or max out a credit card to go to WDW without knowing when or even if you'll be able to pay the debt back. But if it's within your means, it's pretty easy to find plenty to do beyond the e-tickets and water parks.