It would be really nice if each patch came with a few more bestiary entries. Personally I really like the art and lore and it helps to continue to expand on the world.
There are a ton of missing entries for existing zones and it would be nice to see some more entries in the rare and common monster section. I’m surprised things like the other monsters from the fallen family (imp, lunatic, and brute) or the prowlers, tundra wisent, dune wolves, immured, etc. are missing plus some of the minor bosses like the siege breaker beast, torrid one, and even Pyr the intro Helliquary boss. And then of course all the new wildlife and monsters from the Ancients Cradle (there were a few added but it was certainly not comprehensive) and Dreadlands, much of which is completely new to the diablo universe and doesn’t have a lot of background.
This bestiary is by far the best in any diablo game so it would be awesome to make it as complete as possible.
I also think it would be better if the entries just unlocked after you defeated a unique boss the first time or killed a certain number of the given monster type fore the rare and common entries.
On a some what related note, a few new fish species and fishing spots in the Ancients Cradle and Stormpoint would also be nice and make sense given their ocean adjacent themes.