A few things.
First, JRPGs have migrated to the handhelds this generation, something that hasn't happened in previous generations. Plenty of JRPGs have gone platinum on the DS and PSP, for instance, whereas none have on the consoles, arguably because the bulk of the RPGs are on the handhelds.
Second, you're vastly overestimating the power and influence that JRPGs have ever had. Granted that they were the genre king in Japan for long periods (and that they remain powerful there: see above), but as SkyRender aptly stated, they were not the exclusive route to victory. Put alternatively, gamers cannot game on one genre alone. More importantly, only Final Fantasy and Dragon Quest have routinely been platinum games: other series will occassionally reach those marks, but those instances were the exceptions rather than the rule.
Third, your analysis is flawed because you've chosen a terrible place to begin it. The Final Fantasy and Dragon Quest series reach back to the NES era. Why not begin there? You'll find that the NES and SNES had RPGs in droves, but that none of them had sales that approached that of FF VII (*sigh*). You'll also find that in the 16-bit era the SNES had the lion's share of JRPGs, but that its victory over the Genesis was fairly small. Does that not argue against your primary assumption that JRPGs were ever truly important?







