Heavy Rain only existed to be a vehicle to show off the Six Axis controller's capabilities and if you played it at the time it was quite obvious.

This doesn't absolve how fucking terrible of a game it is, and its writing is very beginner's "the twist carries it!" (except the twist falls apart numerous times if you go back and them adding the twist late in development leaves all the elements like the "blackouts" unexplained). But it does go from a 2/10 to a 3/10 if you are the one actually playing it. The tension is palpable at times with you having to actually make the QTEs (many deliberately way too hard for most people to get) and that does invest you slightly more than watching.

Yet even with that minor caveat, it, like all things David Cage, is not worth playing and exists entirely as a novelty to show off technology. Farenheit for the QTEs and the "life sim" elements, Heavy Rain to add motion controls to the QTEs and "branching story," Ellen Page's game to show face capture with Detroit showing it further. This is probably why it keeps getting success, more than anything about the actual games themselves.