Ooh, see, I've got a problem with the implication in the wording of this question. Because it kind of gets into issues of Western historiography in general. "The march of progress," and all that. Newer=sleeker=better. If the OSR has taught me anything, it's not to dismiss older games as antiquated and unplayable just because they're, well, older.
But there's no denying that games go through trends in design, and nowadays we're seeing a lot of designs that are intentionally narrow of focus and light of design. One example that leaps immediately to mind is Cthulhu Dark by Graham Walmsley. This is a system that fits on a brochure-sized foldout, and that uses no character sheet and only good ol' six-siders, yet (according to everything I've read and the couple actual-plays I've listened to - I have yet to play it myself) perfectly captures the significant tropes of Lovecraftian horror gaming.
For a sleek universal system, it's hard to beat S. John Ross's Risus: The Anything RPG. It's more "traditional" in design, in that it uses things like attributes and character sheets, but it also fits on just four pages. Haven't played this one yet, either, however.
Of the games I have played, Dungeon World stands out as another example of a sleek, focused design, this time oriented towards explicating all the implicit elements of the D&D experience. Although not nearly as rules-lite as Cthulhu Dark (frankly, I don't think you could get much lighter and still have a recognizable RPG), it shares a similar focus mechanically in that there's an emphasis on "plug and play" gaming - ideally, the first session should be all improv on the part of the GM, with world-building taking place through game play, and character sheets have pretty much everything each player needs to know about how the game mechanics apply to their character and nothing more.
As a post-script, and in reference to my grousing above, I'd like to point out that TWERPS ("The World's Easiest Role-Playing System"), which featured only one attribute and one die type and certainly gives games like Cthulhu Dark and Risus a run for their money in terms of simplicity, was first published in 1987.
|Plus ça change...|