At this point in my Disney vacation career, the “bubble” doesn’t make much of a difference for me. For many, people immersed in the Disney created world is important. For me, I’m venturing off-site for part of my stay more often, have some local friends I try to make time to visit, and usually buy groceries and sometimes souvenirs at off-site locations, so there are other reasons that lead me to be more likely to stay on property.
You’re a little closer to the parks. Granted, some off-site resorts aren’t much farther away (and those at Bonnet Creek are in the middle of the property), so this doesn’t make a huge difference, but it’s something.
A head start on off-site guests. I don’t always use these benefits, but Extra Magic Hours, a ten day head start for making dining reservations, and an extra 30 days to make FastPass+ reservations are tangible benefits that are important to many. If you want a pre-rope drop breakfast reservation or a visit with Anna & Elsa using FastPass, then the extra time is almost essential.
In some cases, transportation. With Magical Express and Disney buses, boats, and monorails you potentially don’t need to rent a car. In my case, I generally prefer to drive, but some of my friends don’t like to do so when they’re away from home. If you’re staying in one of the Deluxe resorts near one of the parks, then being able to walk to Epcot or the Studios from the Boardwalk resorts saves hassle and usually time as well. If you’re at the Contemporary, then walking to the Magic Kingdom is a plus. Even when renting a car, I’ll still usually take the bus to the Magic Kingdom, since I can’t drive directly to that park, so access to Disney transportation saves time. It’s also helpful to have access to the Disney buses if you’ve had a few too many drinks in Epcot (though I can’t really afford to do this, it may matter to some).
Charging purchases to the hotel room and having items delivered to your hotel is also a useful benefit for many. I haven’t used the delivery option, as if something is too large for me to carry around the park it will probably be too large to carry home on the plane, but that can be helpful if you see something you really want to have, but don’t want to lug around with you all day. The room charges are more of a convenience for me, as I’ve started paying for my Disney meals and souvenirs with gift cards. I could certainly carry those cards around with me in the parks, but charging to my room and then settling the account later is easier than carrying around a couple hundred dollars in gift cards during my trip.
Whether all that is worth paying extra for is completely up to each individual.