What are you saying if you're saying that a game has rpg mechanics? That is plays just like an rpg, but it isn't one? What exactly does that mean?
Also, RP =/=rpg. Yes, the term rpg originally came from RP, rpgs were inspired by RP, but there's a reason why when you think of the concepts, "RP" and "rpg" two completely different things come to mind. They've diverged in meaning, and trying to equivocate them is why you're getting mad not finding and RP in your rpg.
When someone says, "Hey, let's go RP" you don't think they mean they just got NVN and want to play that with you, just as when someone says, "Let's play an rpg" you don't think they want to crack out the DnD character sheets.
If what you're saying is there are no games with RP in them, I'd say that's a valid complaint, but I'd respond by saying that the market for such a game is extremely small and that you shouldn't be complaining about mainstream titles not carrying anything like it.