You bring up a valid point, the Mos Eisley cantina scene is an iconic moment in 20th century science fiction, hell, in 20th century cinematic history. What makes it work so well is that in just a few seconds it establishes that we're truly in a galaxy far, far away. It doesn't hurt that it looks cool and the music really "slaps" as hip youngers are prone to saying these days. Why doesn't a similar approach work for D&D then (for me it doesn't work)?
In 1977, this is something most audiences had't seen before and it wowed them. These days, a similar scene wouldn't have as much of an impact as it did 45 years ago. Maybe D&D is like that. At first, it was pretty cool that you could be a dwarf, an elf, or a hobbit halfling, but it didn't take long before that got stale. So they started adding more and more options. Now we didn't have to be a boring played out elf, we could be a tiefling or a goliath or something.
One of my biggest gripes about D&D is that it doesn't matter what race you pick, and with recent changes in how you pick your lineage, that choice matters even less now. Play through just about any published adventure, and it doesn't matter if your Fighter is a halfling, half-orc, human, or elf. And I suppose this is to be expected given that the adventure has to cater to the needs of a very, very broad audience. I prefer games/settings where there are a limited number of races, but one in which it matters which one you choose. i.e. I want the choice to matter.
But maybe I should lighten up. I ran Star Wars games for years and didn't care about the Mos Eisley effect. We could have a group made up of a Wookie, Sullistan, Chiss, Human, and Bothan and I wouldn't bat an eye knowing that I could replace all of them with humans and the adventure would still run almost exactly the same. Sounds like this is just a me problem.