I don't think that this statement describes the reality we live in.
To me, unikernels feel quite a bit like statically linked server binaries running under an unprivileged UID - but you're choosing not to trust Linux' (or any other kernel's) user separation facilities, but your hypervisor's domU separation facilities instead. In exchange, you lose virtually all of your existing OS's amazing debugging and performance analysis/tuning tools. It's not a tradeoff I'd readily consider.
To me, unikernels feel quite a bit like statically linked server binaries running under an unprivileged UID - but you're choosing not to trust Linux' (or any other kernel's) user separation facilities, but your hypervisor's domU separation facilities instead. In exchange, you lose virtually all of your existing OS's amazing debugging and performance analysis/tuning tools. It's not a tradeoff I'd readily consider.