I have a MSI B450 Tomahawk motherboard and ive had it for a little over a year now. I noticed my bios are from July 2019 but on the msi website for my motherboard there have been multiple new drivers for it since that time, including one that came out earlier this year.
How important it is to upgrade to the latest bios? Ive heard some people say you shouldnt update them if everything is working fine but ive also heard you should.
That depends, usually speaking due to the UEFI being relatively somewhat "security focused", it is almost always a good idea to generally have the most recent firmware specially for BIOS and UEFI.
But from a functionality point of view that depends, generally speaking the new BIOS may or may not improve your experience with your current hardware. Like they might change a few microcodes here and there that might give you better over all experience, OR the new BIOS will make it possible for your MoBo to support newer CPUs and hardware and might have no effect at all on your current hardware equipment.
Always check the accompanying Changelog with the new update to see how it will affect your current setup or if you need it, or any new stuff you think are beneficial to you and your current situation.