What is an Rhaandarite, Paul? Forgive me if it's pretty well known and I've just missed the plot somehow!

JB
Exactly my point! They were one of the TMP background races, sometimes referred to as Vegans (not necessarily of the vegetarian variety). The internal security station was manned by Billy van Zandt and there were a couple more as background extras. They're a race where there is no obvious outward biological difference between males and females, although females wear jewellery. They are very long-lived, they keep growing as they age, potentially to over 10 feet in height. In the TMP Era novel Ex Machina, they are portrayed as having a complex hierarchical society with emphasis on teamwork so they make better followers than leaders. In many ways some of their species background fits Saru quite well.
Admittedly, the makeup in Discovery is more interesting, but I just despair at the introduction of new 'established' race after new 'established' race instead of applying racial tweaks to create cultures as well established as the Vulcans.
Similarly, Efrosians have almost no canon culture or species traits. Make his skin dark blue and you have a re-imagined Betelgeusian!
I am probably biased since TMP started the ball rolling with its new races, but I had well over a year to absorb and let my imagination run riot over the TMP aliens because so much merchandise came out before I watched the SLV on Itv. I loved the notion of an asexual warrior race that reproduced through cloning (Arcturian), a race where men and women look identical to outsiders (Rhandarite), a religious predator species who was a humanoid eagle/ leopard hybrid (Betelgeusian), a species with an acute temporal sense and ability to affect the time stream locally to effectively 'teleport' very short distances (El-Auran, I mean Kazarite - who also maybe look like Ktarians), Fluorine breathing aliens with superior vision and electromagnetic senses (Zaranite), an empathic species that can sense and manipulate pheromones and influence brain chemistry (Deltan), and a robust Saurian species with excellent lung function to allow them to survive hostile environments while producing excellent alcoholic products (Saurian).
Any of these would have been more fun than the poorly thought out Betazoids.
When I look at the bumpy headed monocultured one-off species that we got, it just feels like a missed opportunity. Compare Trek to the recurring pak'ma'ra, Gaim, Minbari, Vree, Narn, or Centauri. Admittedly, the Brakiri were a bit lame and the Abbai were merely a thumbnail, and the Vree were most often a joke ( in that they'd been joy riding to Earth and tormenting the natives for centuries) but even so...
I suppose DS9 did work a bit harder since the station was stuck in one place.