So, this is a microkernel. Could anybody please explain me why microkernels are so great, when practically they do nothing more but push the overhead of switch

So, this is a microkernel. Could anybody please explain me why microkernels are so great, when practically they do nothing more but push the overhead of switching threads to extreme? Basically, everything that program does requires waiting for scheduler to execute whatever service we send messages to. Disk, sockets, devices - everything. All of which is made in the name of memory safety. On the other hand, unikernels that execute nothing but managed code (e.g. not code of CPU, but code for some virtual machine such JVM or .Net, which is forbidden to read other processes' memory on the syntax level) solve the same problem of protecting system memory, while carrying much less overhead. I guess this approach would be more preferable for creating a new mobile-oriented OS that requires good performance and low power consumption, no?