Did any PlayStation Classic title ever go viral? The game was among the Top 10 PS Classics of the year it was released in, which is really good for such a niche game.
But if you need reasons: it was released as a PS Classic and thus only playable on PS3 and Vita - at a time when the PS4 was already out for a year and gamers started to change systems. Konami should've invested some money, give the game a small overhaul and bring it to PS4, similar to what Square Enix did to FF VII (which was also released on Steam). That'd have a greater chance of success.
Also, rarity of original games don't guarantee success. The closest I can think of would be Earthbound and Earthbound Beginnings, but even these games don't gain much traction, and Nintendo refuses to release Mother 3 int he West.