The Dear Esther remake is quite clearly a love letter to the mod, and what can be accomplished by visual artists in videogames when they're given complete freedom of time and control of their work.
Its just the one guy, if I recall correctly. The former DICE employee, spending his own time and talent towards a single product. Because its just him, in his own time, for something he loves, he can customise every texture, shader, and polygon to look absolutely exactly how he wants. No spamming of reused assets, no stretching of hideous textures. No time constraints, deadlines, or expectations beyond what he himself wants to achieve.
This kind of polish is extrodinarly hard to accomplish in a normal development cycle, simply due to the amount of people involved, the budget given, and the time required.