I think it's a bit silly of Disney to require me to have a reservation to have an Uber driver pull up to the main entrance and drop me off, though.
I don't, for two reasons.
The first is the pandemic.
Hotels are already problematic for transmission. Requiring people to either be overnight guests or have a dining reservation allows some degree of control over density within the space. Disney's first concern is to make sure people feel safe staying in those resorts, because those people are paying $500-$700/night to be there.
But, even aside from that, Seven Seas Drive is a two-lane road that has to serve all inbound and outbound traffic for Poly and the Grand Floridian. Likewise, the stretch of World Drive north of the Seven Seas/Timberline intersection is a two-lane road that has to serve all inbound and outbound traffic for BLT and the Contemporary. There is
no way either could handle even a fraction of the traffic that would result from every Magic Kingdom guest "just getting dropped off" in a car.
But, whether I think it is silly or not doesn't really matter, because at the moment they are requiring it. You can make it and no-show for it, or you can park in the TTC like everyone else. It's up to you.