Pokemon is special, so there's no sense comparing anything else to it. The Dragon Ball games are all licensed games attached to a genuinely legendary, beloved, and iconic bestselling manga and anime series, so comparisons to it are likewise tough. Dragon Quest isn't popular outside Japan; it is niche. It typically struggled to a million units in the west, which it did thrice (the original, thanks to Nintendo giving tons of copies away, VIII, as Square had the good sense to bundle the highly desirable Final Fantasy XII demo with it, and IX, when the DS was white hot.) More recently, XII is closing in on two million units sold outside Japan, but that took well over three years worth of time, ports to every platform under the sun, huge price cuts, and an S re-release. I'd argue the art style (Toriyama or no) and turn based combat hurt it.
I wouldn't put it all on art, no, but art is a big part of it. Two other things that hurt JRPGs in general are turn-based combat, rather than action, and a linear story, rather than open world.
Dark Souls is a bad example, as the third installment has sold over ten million units, as of March 2020, with most of that coming from outside Japan. It has action combat, and a non-anime art style. Monster Hunter World is another example of a Japanese game that broke out big, selling over twenty million, combining the original game and the Master edition. It has action combat and a non-anime art style.