IPC overhead was primarily an issue with the Mach kernel in particular (due to it performing elaborate checks on message ports) that later ended up unfairly stigmatizing the entire microkernel design in general.
Contemporary microkernels like L4 are much, much faster.
In theory you can postulate the performance impact is worth. In practice the is much more in it. That is the difference between computer science and software engineering.
What about IPC overhead?