I guess I'll be the lone dissenting voice...I don't dislike DCA by any means, but I could easily take a trip to DLR and skip it. At most it's a half day thing for me, especially if I'm with my husband, who doesn't ride any "scary" rides. Really the only rides I actually seek out there are Little Mermaid, Toy Story Midway Mania, and Soarin'. I like RSR okay but I'm not a big Cars fan. I also don't find Carsland a reason to go to the park. Is the themeing great? Yes, it's very well done. However, there's just not much to DO in Carsland, besides take a walk down the street, get in your one or two RSR rides, then move on to somewhere else. Same for Bugsland. I love the themeing, but the kiddie rides leave much to be desired for two adults. I used to like Tower of Terror and Screamin', but I'm not that excited about thrill rides anymore.
I do think that the area near Grizzy River Rapids is very beautiful and relaxing. That is my favorite area of the park, because it reminds me of camping in the Sierra Nevada. But honestly...I'd rather just actually go camping in the Sierra Nevada. So for me, DCA is easily skippable. Now, if this is your first and probably only trip to DLR, then I think you should definitely get park hoppers and experience it! However if you know you'll be back, I would say it's not necessary to go to DCA on every single trip.