I would't pay $800 for the Grand Floridian, either, because that particular resort isn't my cup of tea. But that doesn't mean I don't see that it might hold value for other people. There are circumstances where I would be tempted to pay rack rate for a few nights at a resort I do love, like the CR or the Yacht Club.
For my family, it's always been about ease, comfort and special touches. When we had toddlers, there was nothing better (IMO) than staying where we could walk to a park or two, take a monorail or boat to at least one more park, and rarely if ever have to deal with wrestling a stroller onto a bus. Add in the opportunity to sit on the balcony and watch fireworks burst over the Castle while my kids snoozed peacefully inside, and we were pretty much entirely sold on staying onsite despite knowing that it's crazy expensive. We have ever stayed offsite and it was a fine trip, but on the whole we prefer onsite and are willing to pay for it.
Our tradeoff is that we take fewer trips -- our upcoming trip (at the GF on an AP discount) will be our first in 4 years, and the next interval is likely to be much longer if prices keep going up. I have a friend whose family spends 6+ weeks every year in Orlando/Disney, staying offsite in a timeshare, and they prefer that. And while I know that the $250ish she pays for a week in an enormous condo is objectively awesome, I don't really want her vacation (and she doesn't want mine). It's just different styles.