I have given much thought about the the old-school movement and all the retro-clones, and near-retros, and such out there. Not just D&D-clones, but also games like Mazes & Minotaurs and Encounter Critical. M&M and EC are both examples of making a modern game that feels vintage and even makes-up a tongue-in-cheek backstory about their creation. The stories are fictional, but in the case of M&M, it was a good parody of real life events.
I see the necessity of games like Labyrinth Lord (Basic and Expert D&D) and OSRIC (1st ed AD&D) to keep the older, unsupported rules in-print. They are doing well because there is a demand for them, as a lot of older gamers are coming back to the hobby (or they what to introduce them to their kids), but they need replacement books, and there is an interest with younger players who have become disenfranchised with the newer D&D or just what to discover the game's roots. On the other hand, a game like Lamentations of the Flame Princess Weird Fantasy Role-playing Game: The Grindhouse Edition (damn that is a long-ass title) is basically the older D&D rules - a mix of original, with basic & expert - with a good amount of useful house rules, and artwork tailored to the creator's personal aesthetics. This was not made to appeal to the general gaming market, or to tell people what D&D *should* be, but it was the expression of one man who made a rulebook uniquely his. Folks might write it off as a typical "fantasy heartbreaker" (a published indi-RPG that is based off D&D, that tries to compete with it), but to me it is a work of art.
The D&D rules are universally understood by most gamers, and with the malleable nature of RPG rules, plus the unusual legality that liberates them from copyright regulations (with the OGL as a great redundancy), it is only natural that fantasy heartbreakers become an art medium into itself. I already see RPGs in general as an art medium. Its like poetry, in which you have metrical composition (the rules), themes (the setting or genre), meaning (the scenario), euphemism (mata-stuff), and expression (the adventure). In this case, a fantasy heartbreaker expresses itself through house rules, supplemental material (new classes, spells, monsters, etc.) and artwork. To me, what makes a fantasy heartbreaker work is not just throwing is some house rules and ripped art into a carbon copy of the core rules, but to craft something that is meaningful and feels unique.