Horror works best when peering through something with limited visibility. We see this in horror films, Haunted Mansion takes advantage of this, it's pretty standard. Being a horror attraction, both versions of TOT work. You are trapped, backed in a corner, and the doors keep opening on spooky tableaus. There's a stillness to them, that's why they are small by design. It's a creepy vignette where we see unusual things before the doors close on us wondering what we just saw and experienced. Each time the doors open there is fear. This fear eventually pays off with the view of the heights you have ascended.
Guardians is not horror based, but action based. It puts the guests into a high energy prison break with blasters and such. With DCA's limited design, our experience will be limited to having the doors open and seeing mayhem on the floor. We aren't amongst the mayhem, we're just seeing it unfold. With WDW's attraction, the 5th Dimension Room gives us the chance to be in the cross fire. We need to escape the current shaft while the Guardians provide cover and we make our way to the escape hatch. The trackless design also means that we can face to our right watching a scene unfold and then the car reacts by turning and seeing the 2nd half of the scene on the left. This allows for two different coordinated show scenes to unfold around the guests. The bottom of the drop shaft also has the space to feature a Groot and Rocket AA if wanted whereas the DCA version is boxed in with the car occupying all of the space.
DCA offers a limited retheme reliant on projection and sound whereas the WDW Tower can expand that into a full attraction because they have the room for Animatronics, an exit scene, and vehicle movement to put guests in the middle of the action rather than watching from the corner.
I also think WDW's biggest problem right now is the lack of rides that appeal to teens and young adults. I spoke with many Florida residents upset with the new Mine Train coaster because they thought Disney was finally going to give them a reason to revisit them instead of Universal. While I love TOT, I do think an explosion filled superhero attraction would appeal to them more. Also, a Guardians ride seems to fall right in line with the revamp of the Studio park. Star Wars, Toy Story, Muppets...90% of the park will be based upon IP based lands. It seems odd to have the Hollywood themed entry area expand to also feature 2 attractions. I'd much rather see Disney use the area surrounding TOT as a Superhero based area that outshines Universal. With Disney California Adventure being so tied to California imagery and settings, such a large Studio park style attraction seems out of place.