I would have loved Doku too.Well...not really. I can't speak for Momiji too much (people say she's a variation of Hayabusa), but Rachel is a spinoff of Nicole, with a moveset more geared towards juggles than the former was.
Either way, I woulda rather had new stuff than all this Ninja Gaiden content (characters, costumes, stages, etc)
Except I woulda loved Doku, I admit.
Nicole was a spin-off of Bayman and Leon, with marginally longer strings, and that epic 41236T and Sacks 2H+K. And Rachel was a "Nicole-with-a-twist" lol.
If we had Nicole instead of Rachel, then she would be Xbox exclusive, and we don't want that, no no. That stopped with MK9. From a marketing standpoint, I would include my own character, rather than pay someone else to use theirs.
Rachel is still a very good character, more or less. The additional characters for 5U were really good.
Now onto Momiji. Momiji is a character who has 4 moves that were taken from Hayabusa, (I believe) because she is from the village, you know, how all the Mishimas have EWGF. These are her 236P, 6P, 8P, and 236P+KPP:Izuna. Her playstyle is unique, but still similar to her teacher, Hayabusa's for a completely obvious reason. She is very different to her NG counterpart, though her throws are directly taken from NG2 and 3, for memorabilia. Her arsenal is a lot broader than her NG form, and also, this jumping thing (Don't know what the stance is called) are to my knowledge, New additions to her moveset. Momiji also forces people learn her attributes. If you don't learn that, you'll be caught in a dangerous trap.
I still think that there could have been better additions to 5U, but still, these characters are still VERY, VERY good.