I'm a little worried that this could easily decay into unhappiness on all sides. I'm inclined to think that we're probably misunderstanding one another, or even ourselves, to some extent, and I'd like to find a way to resolve that so we can all walk away happy, since I'm pretty sure we all have a great deal of love for our little lead people.
Let me delicately and carefully ask: Do you mean that the detail is more fine or that there is more of it? Or do you mean something else?
And take your time answering and read the rest of this first, please. There are gods and glass toes about in equal measure. And maybe some egshells and tripwires tied to things that say "this side towards enemy.
Okay, here goes:
Finer (smaller) detail could possibly be an example of a real "advancement", though most likely not because of any advancement in sculpting technique. More likely changes in material or casting processes. There have been changes to the way we sculpt, of course, as we have more materials now than then, but mostly I think that makes certain kinds of things less time consuming. I don't think there's really any level of sculptural detail we can achieve now that ancient Greeks couldn't achieve near on three thousand years ago. We can do it faster . . . but not "better." And we can maybe make more copies more quickly and more reliably and with greater fidelity to the original, but that's not sculpting. It's casting. (Or printing. Or milling, for that matter.)
I would think there's a pretty hard physical limit to the smallest detail that can be practically spin-cast in white metal; its "resolution" if you will. And I'd also guess that late 80s sculpting approached that limit about as closely as can be measured with a Mark I eyeball. (And indeed quite probably late 40s sculpting as well.) Polystyrene injection molding can take a finer level of detail, but it requires a quite different approach. (And yields a very different look as a result.) And even that has limits. If you really want fine detail you have to learn to bend and solder brass, and stretch sprue, and all manner of insane (but sometimes fun) things that simply cannot be cast.
Honestly, any method of reproduction one might wish to use will have certain limitations that will force the artist in certain directions. Some of this stuff influences style. And style can influence what method of reproduction is preferred. I know that with my own music I have to think pretty long and hard about how I'd like it to be produced or reproduced. And it never ever comes out quite the way I envisioned it. (Closer now than when I began, but it's a long slow fight.)
My experience with modern miniatures is a bit limited, as I simply don't care for many of them very much. In part, I suspect that's because most of them strike me as quite busy; too busy, in fact, to seem "plausible." Busy, in this context, could be more or less synonymous with "more" detail. And that's more or less a stylistic decision, albeit one that can be influenced by your chosen production method.
Anyway, I don't want to go into this too much, as I'm probably about the least experienced person on this board that's actually tried to sculpt a miniature to some extent. (Sort of. A little. And I know darn well some of what I've done could not be cast. Or at least not economically.) Maybe I see what you're driving at? I think? And I think most of us would regard that as a stylistic choice, rather than an "advancement" per se. (Again, maybe.) There's certainly room to prefer the current stuff. And many of us would admit that there's some dreadful stuff out there from the 80s. Just . . . maybe not the Jes Goodwin Eldar. Some of those are absolutely legendary. For a reason. One does not insult Beethoven V lightly in the Grosser Vereinsall. And I understand. I've grown weary and insulted the masters once or twice (or rather more) times myself. (Always to my own embarrassment when I realize how wrong I was later on.) And maybe we're a bunch of curmudgeons that come across as "oh, all that modern stuff is just noise" sometimes. And that's probably just as wrong. But it is wise to realize where you are.
There's a lot of folks on here from the Vienna of miniatures wargaming, who play in the Grosser Verein-Foundry. (And others of us who are jealous and wish we did.)
Anyway . . . back to your regularly scheduled show and tell. (And I am looking forward to seeing your eldar all decorated up.)