@iska I'm pretty sure the provided MIPS designs are proprietary, so them being royalty-free wouldn't fix the problem.
I'm pretty sure the patents on the base MIPS instruction set, plus a number of extensions should have all expired by now - so you can indeed re-implement the base MIPS instruction set plus some extensions without having to pay royalties.

The example RISC-V hardware designs are under a license that results in the design being a free hardware design.
Sure the design is royalty-free also, but that's really an irrelevant thing.

As for currently produced RISC-V designs that end up being fabbed, they're all ultra-proprietary and have patents up the wazoo.