Nuendo Needs 16 FX Send Slots Available to Keep Up With Today's Workflow

I do agree.

Just to contribute some help if you haven’t done this already your self. In my project templates I’ve set up dedicate ‘Group Split’ Tracks that have no output and only sends.

Each primary instrument gets its own.

Vocal Track
Vocal Track Sidechain Split
Vocal Track FX Split

Guitar Track
Guitar Track FX Split.

In the template, everything is already routed and ready to go, including to some preconfigured FX tracks I use regularly.

You might also be interested in this FR of mine in the Cubase forums:

Integrated native plugin Chainer Insert (Steinberg official “wrapper”/Insert expander) - FX MATRIX - Cubase - Steinberg Forums

Not entirely relevant, but does deal with expanding user programmability/routing of FX.