As it gets ever faster, cheaper and easier to generate large amounts of source code, the bottleneck continues to shift toward the review side of things. It's faster to generate lots of code than it is to read, understand, push back on, or approve lots of code, and the balance of effort between those two sides is tipping hard toward reviewing.

There's as much value for the author of a PR in splitting it up and making it comprehensible as there is for the reviewer. The value of what software engineers do was never the code they output, but the systems that emerge as a result. Working on comprehensible pull requests helps the author make sure they fully understand what they're submitting, as much as it helps the reviewer grok what the hundreds or thousands of lines they're being asked to review are all about.

What code review is actually for

One function is obviously to find bugs, and agents are increasingly good at that, for the same reason they're increasingly good at writing better and better software in the first place.