My understanding is that after the initial rush to see the new thing the goal was ultimately missed. It didn’t really bring any renewed interest to the park. So between Guardians of the Galaxy - Mission: Breakout! and Pixar Pier we’re looking at over $200 million spent on redoing parts of the park that didn’t really need to be redone, one of which was just redone relatively recently, that also didn’t really generate more interest in the park. That was more than enough to add one big new ride or a couple smaller ones (and smaller being The Little Mermaid sized) to really draw more interest. It should have been enough to have a new E-ticket open with Avengers Campus.
Of course the goal was going to be missed: reskinning an already-popular attraction will never result in sustained attendance growth.
While DCA's Tower of Terror never quite reached the popularity of WDW's, it was still one of the park's headliners. It was only a walk-on during the earliest and latest hours of normal park operations; otherwise all seats were being filled all day long. The ride really didn't have a surplus of capacity that was going unused, so there's really nowhere for the ridership to grow. Whether guests are waiting 15 minutes or 60, only a certain number of people can ride it during a single day.
Similarly, the Pixar Pier project overhauled the already-popular Paradise Pier attractions by slapping familiar characters on them. It added a couple snack kiosks, but otherwise only dealt with aesthetic changes. The attractions (especially California Screamin' and Midway Mania) were already popular, and rarely sent out empty seats. A few years after the project opened, the area is about as popular as it was before. Which of course makes sense, as once again the previous design didn't have excess capacity.
My understanding is that Mission:Breakout was done "inexpensively" (by WDI standards) for somewhere in the $40-60M ballpark; I believe Pixar Pier was $225-250M. Between the two projects, they spent around $300M on the park and added literally no capacity other than a couple ODV snack stands. The short-term attendance bumps associated with both projects are most similar to typically-inexpensive seasonal promotions and holiday decor, not permanent modifications to the park.
On the flip side, the Universe of Energy is a great example of something that could have benefitted from being redressed into a new attraction. It struggled to fill even half of its seats, and provided a unique (and long!) attraction experience. Instead, they're completely replacing it with a rollercoaster that presumably has middling hourly throughput. And while Cosmic Rewind may average higher ridership than Energy did in its final years, it will never come close to its total capacity, providing a nice "emergency release valve" for when crowd levels in the park got too high. They're spending about half-a-billion dollars, and the end result will be an attraction with a smaller capacity and far shorter ride time.
Not only does WDI require outrageous budgets for anything they touch, but their projects seldom provide meaningful improvements to the parks they're in. It's no wonder that new things are built so frequently, when the return on investment is so unbalanced.