Apple CarPlay support is one of the most requested features if you read Rivian forums and subreddits. In a live Q&A session on Instagram, Rivian head of software Wassym Bensaid was explicitly asked about Apple CarPlay. The answer was more nuanced than Scaringe's, although it sounded a lot like GM's justification. Rivian's software wizard said that offering CarPlay would've been the easiest solution, but he wants to do more for its users.
More specifically, Rivian aims to offer a fully integrated and seamless experience, as the navigation system can estimate the charging stops and range based on a driver's habits and vehicle settings, including ride height. This is only possible by designing end-to-end software solutions. Still, Wassym admits that Rivian navigation doesn't offer the best experience today. Things will improve, though, as Rivian will overhaul the trip planner to allow planning your next adventure from the comfort of your couch.
Wassym also revealed that his team is working to bring more requested features into Rivian vehicles, starting with a voice assistant and then text messaging support. Considering how awful car voice assistants are, this sounds like an unfortunate development. Wassym's claims that its voice assistant can be better than Siri are bizarre. He also doesn't explain why Rivian can't offer all of the above plus CarPlay integration. Ultimately, it's all about control, as Scaringe explained earlier.
Wassym Bensaid also talked about an expected improvement to the towing mode. An upcoming update will enable the bed camera while towing, and the truck will better estimate the trailer weight. This will be one of the biggest updates that Rivian will offer this summer, bringing more towing performance to its electric trucks. Another feature very close to a wide release is the Rivian Drive Cam, along with improvements to the Gear Guard.