Does anybody actually care about Yakuza or especially Yakuza of the End though? Seriously? This is way cooler. Who isn't sick of zombie games yet? I'd much rather have a Layton/Ace Attorney game set in the past. That's original. Not zombie Tokyo.
I'm... Not quite sure what you're trying to argue here, since I never did mention popularity. I mean if that's the case, I'm not quite sure what we're doing here on a SEGA blog, I think it's time to shut up shop and open NintendoBits. Heck I'm not sure why you're more excited about Phantasy Star, didn't you know Yakuza is the bigger series?
And cooler? I think running over zombies in a forklift then getting out and shooting them down with a gunarm, finally finished off by playing baseball with grenades is probably going to be much cooler than anything this crossover game will ever achieve.
As for originality both games have this much, zero. Yes one has zombies, very unoriginal, so is robots, wizards, humans, commies, capitilist dogs, aliens, the devil and pretty much anything else you can think of.