Because they are significantly more numbers than the average BlazBlue game which the game's framework is based on and we have a generation where once heavy hitters like Tekken, Dead or Alive and Soul Calibur struggle to sell 200k. Street Fighter is really the only real major success story for traditional fighters (and much of that success comes from the West anyway).
Well we don't know as per Ni No Kuni since we have no precedence for a Studio Ghibli RPG. Studio Ghibli certainly has a presence in the west that could have worked to its favour but we just don't know how that game would have fared on PS2. As far as traditional RPGs go, it is really charming and accessible. This does not translate to big success for SMT, though, which couldn't be a more different type of experience. There are always going to be individual success stories here and there: even on the 3DS we saw it with Fire Emblem and Bravely Default, but that's not enough reason to extrapolate those sales as an argument in favour of a relatively obscure franchise like mainline SMT. But I can't say you are wrong since we'll never know. I just know that the last SMT game with a decent budget sold around 70k in the US
As far as Tales is concerned, Symphonia GC is still by far the most successful entry in the franchise in the west and really was the anomaly when we look at the big picture. There's been growth sure, but only really because Namco is bothering to localise more Tales games. The individual entries still mostly do <200k in the US. Symphonia GC did >400k.