Actually another reason people use the architecture is for process level isolation, i.e. limiting the blast radius of memory corruption. But in both cases, Im sure you could design an ergonomic RPC framework that takes care of offloading computation mostly transparently behind the scenes :)
But TBH, in a Rust world, it’s worth revisiting the assumptions behind the ROS node architecture, since Rust is so strong at scaling to large monolithic applications (due to the strict hierarchical code patterns it encourages).
A transitional Rust approach, that doesn't try to reimplement everything from scratch, could do something like a strangler pattern: Take each ROS node, run them separately in “jails” with a Rust API around each one, then implement the plumbing/management logic in pure Rust.
https://docs.rs/itertools/latest/itertools/trait.Itertools.h...