DCA was a great park back in 2015 after Condor Flats was renovated and before Soarin' was changed. If it continued on that path, DCA easily could've been the second best stateside theme park with the only one better being across the Esplanade.
I actually agree with you. Even though the outdoor Test Track, um, er, Cars Land, ride is fantastic, I liked a lot of the research and love for California that was put into the park. It was landlocked and had cheap carnival rides put in, which affected its value, though. But I think if they had had more budget and time, it was on the way to something uniquely California, and good, I think.
And like other Disney parks, I think some smart use of IP would have worked without compromising the California narrative that was going on, and which matched the Grand Californian that was part of an entrance. Even the landscape of the Grizzly River Run grew.
But overall I think the park suffered from a perception of cheap off-the-shelf rides (including even the Grizzly River Run itself, but especially the pier area rides) that proliferated and were not up to the standards set next door. They were literally building next to the most iconic and revered theme park -- the one that defined "theme park". So to have so many off-the-shelf rides so obvious really hurt it, I think, despite beautiful and well-researched theming.
The theming would have succeeded with more well-done, Imagineering-quality rides. And, yes, Tower of Terror could be included in that idea -- they even built that on the cheap (smaller in scale). But I do think its theme was perfect for the area. And when I rode it, the cast members were much more "into it" than ones I have encountered at WDW.