I plan to do one for sure because I hate that they share the same face. I've wanted to try playing as Honoka but her appearance is a little offputting to me so I may do a full overhaul on her. Marie Rose I will probably just redetail at a higher res, because I like her face overall.
I might be a bit out of subject here, but I really wanted to point that out :
Honoka's face "incident" put the light on a very interesting physiognomy point. I checked her face's model, and as I stated before her eyes form is different from MR's. The rest is nearly the same, excepted for her make-up
So they basically have the same face, minus one detail... and that detail appear like a major difference for some (like me) and was nearly insignificant for the other. It's just like the "dead eyes" syndrome of the FF film that led to the fusion of square and enix, a little thing make it all.
This, on a modeling standpoint is really important. When you look at Kasumi's or leifang, they doesn't appear to have the same face. But they are really similar. Their "construction" is nearly the same as they were constructed with the "same" idea of "beauty", that is a face "proportionate". Long story short, when we look at a face, we tend to globalize it's shape, and the detail that stand too much out are considered ugly. Thus, on a large scale study, it was proved that we prefer a "normal" one (by that I mean conform to the norm). If you take a look at all the DOA's girls, and check their models without textures, you'll notice that their faces are all pretty similar. All of them are constructed on the same base that we all use to create "beautiful" girls, and then some variation were added.
So in the end, what make them look different are "details". And those appear different depending on the person, the light, the angle...
I think that kokoro's face is strange due to a detail that appear odd, if we can change that, she will look gorgeous. If we're going to change how the cast look, and if we want to preserve their characters, we must work with that in mind.
Just my littles coins on the matter.