Plarail Kenji Set is not Popular?

Yes, but they do still have higher standards in quality of materials, rubber traction tires, and run on Tomy track.
It is just the condition of the world these days.
There is no alternative choice.
Maybe all those Chinese counterfeits will end up being the superior quality product someday sooner than we think.

So true, Muddy.
At least we could actually run these counterfeits on our blue track, and we can't run new Fisher-Price-Mattel engines without severe modifications. And even with the modifications they will still have problems on some "special" blue tracks, as I have seen in many videos. The two systems are (thanks to Mattel) now incompatible. On the other hand, Chinese are getting better and better, and those counterfeits could be even legalized one day, who knows?
But I still firmly believe Tomy would not give up. Plarail is so loved in Japan, so I hope this set is just an occasional flop, and many more excellent trains and sets are still to come.