IMHO, anytime they write "stability" or "memory compatibility" is a pretty compelling reason to update. Modern systems run pretty close to the edge, and DDR5 has some nasty training times that maybe an update could help with. How much you care about security fixes for microcode loading or boot time stuff is up to you... some of that is pretty esoteric, but some people are compelled to have all known security fixes.
Updates to support new CPUs are a maybe... I can probably wait and run that update right before swapping cpus, but some people might prefer to run them now, in case their cpu fails and they need to replace it ... a lot of boards can flash without a cpu installed, but you get a lot less feedback, it's nicer to flash when things are working.
> DDR5 has some nasty training times
I was having a hard time figuring out what’s wrong with my new system, until I read an offhand comment about DDR5 having long training times on AMD, and I should just leave the system running for 5-10 minutes… sounded like an urban legend, but turned out to be reality.
Yeah, it's super frustrating, I'm happy I knew about it before I did my ddr5 build. And then my board has this cool feature where when I load the XMP/EXPO profile from the ram, it turns termination from Auto to Off, and won't boot... sometimes it figures it out and goes back to the JEDEC profile, but usually I have to clear the CMOS. Tons of fun! And latest BIOS does the same thing, I updated recently cause I was having weird things, which did go away but not sure if the BIOS update or new fan settings helped more.