It seems like this cell barely evolves, because the system they built for duplicating the DNA makes very few errors.

Natural life tends to evolve, which may have consequences for production.

For example, quorn production has to be restarted from a seed population after ~1000 hours because it tends to evolve colonial variants that break the product standards: https://www.davidmoore.org.uk/21st_century_guidebook_to_fung...

It's desirable to have some kind of simple base to start from that is an easy-to-configure platform to deploy any kind of metabolic machinery.

Their "minimal" cell is not quite a minimum product because it depends on prebuilt ribosomes and can't reproduce on it's own. No danger of gray goo!

This is more like it

https://www.jcvi.org/research/first-minimal-synthetic-bacter...

but those guys could probably add components to their cell to make it truly self-supporting although in biology there is a big difference between "barely works" and "high performance"

It seems that eventually you could build much more flexible and powerful if you build from scratch. Hacking existing cells is a shortcut but longer term we may get grey goo.