Responsive web design—and with it, resolution independence—has certainly brought web design back to flatness, grids, and boxes. But isn't that what web design is, manipulation of boxes and grids? After years of textures, backgrounds, shines, reflections, drop shadows, letterpress, and "faking it" by stitching together elements derived from Photoshop, I think a return to browser-native design is refreshing.
I'm gonna take Mr. Storey's suggestion. Thanks to everyone who contributed. Branch closed.