Disney's differentiating factor is that they can/and have, created compelling beautiful environments, places, spaces that people want to spend time in. New Orleans Square is not littered with puns and gift shops with giant cutouts of characters adorning the entrances. They create space first, and the character stuff is so lightly used that it isn't aggressive. It is there for the people who want it. Or dark ride experiences and character experiences are hidden in show buildings. You are correct.
Six Flags gives no consideration to land design once their parks are in operation. At the park I grew up near in Chicago, each new attraction actually had a detrimental effect on the park; they just added one of those ridiculous "4D" green lantern coasters (jk; the Joker, but if you are familiar with the Green Lantern at magic mountain, its a similar ride system and footprint) and cut across a. a stream that used to be crossed over via a covered bridge that divided one land from another (mardi gras/orleans place from some new england thing that they'd already littered with DC) and b. green space that extruded into a walkway parallel the bridge. It used to be that as you approached the bridge, a vast park plaza with two midways on either side, sprawing 150-200 feet wide that would enclose a park/gazebo and midway games with retail and dining locations would then choke up again to enclose that space into a recognizable park, and give a 20 foot wide or so path a 50 feet or so approach to the bridge where you'd enter the next land. Now, that whole thing is screwed up and without the planters, and instead a giant concrete block on which this green lantern coaster was built, the two lands fade together and the sprawling, hot, unshaded midway that once surrounded a gazebo never ends and just fades straight into the next land. It isn't abysmal, but confusing, and the plaza/approach to the original batman: the ride (the world's first inverted coaster that was custom-built for this chicago park location) is messed with now. Similarly the dips below grade in all the cloned versions (think the cement cutouts here in california in what is otherwise a bed of rocks) go toward those streams and around weeping willow trees. Now, there are still some/most, but they did cut through much of that. Out front, they put a disgusting red and white striped gazebo that doesn't fit the new england or gotham architectural styles. So now, there is a giant green and purple coaster, 10 feet from a red and white striped gazebo, its nauseating.
Disney has the ability to spend money on land design. That's what makes Disney feel like "disney." Without that, you can have all the characters you want, but it'll still feel like a cash grab. I'm not sure how wdi works in-house, or how parks are managed. Is there institutional knowledge? is there a team that has been working on and managing each park for a decade that knows how all the elements and lands speak to and compliment one another and create a cumulative effect of a park experience? Because with more and more project-hire contractors, design teams thrown together with no previous experience with said parks, hired by P+R and WDI to deliver something fast, there are no doubt going to be decisions that are made that don't fully make sense on both sides of that equation. I think the advent of Pixar Pier is happening because pixar is leaving the rest of the park; that shows some strategic, holistic thinking actually. But the focus in all of these cases, marvel included/especially, should be on creating compelling convincing WORLDS to explore. If they just throw a spiderman dark ride show building where a bugs land is and throw an avengers show building next to guardians and none of these things do anything to speak to one another or create a believable cityscape, then it doesn't matter how much money goes into the shows/rides, the place will be a complete dud. You won't see people hanging out there, sitting on a bench, taking pictures of the environments, etc. Think again about New Orleans Square/ROA or adventureland (since sadly, TL is a mess of an example despite having some popular rides, and fantasyland has flat rides but it is diegetically appropriate since the ride aesthetic is a contributing component to "fantasy). Splash mountain, Haunted Mansion, Pirates of the Caribbean, Big Thunder Mountain, all in the round, soon to be joined by two star wars E-tickets on the other side. Tons of foliage and the show buildings are either seamless extensions of the landscape or of the city/townscape (Pirates and Mansion). You don't just stand there in the hot sun and think, okay what do you want to go on now? This ride or that ride? how long are their waits? Well I'm already melting I can't imagine standing in a ride line, etc. etc. It is made so easy, comfortable by comparison. The beauty of the landscape, whether its the shaded bamboo queue at Indy or the plaza in front of mansion, and how those aesthetics or environmental conditions appeal to you and what you desire in any given moment (more sun, more shade, indoor, outdoor, old west, french quarter) ensure that even the queue and the surrounding environment can be a contributing factor in determining where it is you want to be and what rides to go on.