Well we did get another Ninja and returning DoA character. I'd say it's a fair trade. Unless we get another VF character. If that happens, I don't really have a comment for my lulz.
You had four ninjas. Now we have five. 5= no. 4 is acceptable. Besides, with Jacky being here now, you'll be running into nothing but Jacky. You hardly run into Akira as it is. So personally, I don't mind that addition.
We had 7 ninjas in Dimensions :V 5 is nothing, especially in a game in which the plot centers around the ninjas. Plus most of it is just personal bias. I dislike guest characters, but hey; the more, the merrier.
Do I see an assload of DOA ninjas in VF? No. Why? They don't belong there, just like Virtuas don't belong in DOA. I don't mind Akira and Pai so much, but if Jacky is anything like his sister I'm gonna be putting up with twice the bullshit.
Any type of character can belong in any type of game. It's just whether or not the players like those type of characters in the game or feel they belong. So most of these comments including mine, are just personal bias as Nightpup said. I'm all for the idea of characters invading other games. I mean, I'm a SC vet and we had Star Wars characters in the game.