But less is more. HA!:devil:more is better,
But seriously. If you think about the idea of having more than one playable character then we should see it from the point of view of how Capcom would do it. Second playable characters or unlockable characters aren't exactly new, even the original RE had this, Onimusha, Bayonetta, and any other game that you might associate with DMC, which in the original Trish was going to be but budget and release dates prohibited it.
What are some of the most recent games with a large cast from Capcom? RE6 and RE:Revelations 2.
With RE6 the game ended up been a weird mess because each pair of playable campaigns were a different genre, it lacked focus, there was too much in too little and all of the campaigns suffered for it.
RE:R2 had fewer characters. Two campaigns with 2 characters each, which was a classic RE way of doing things and it worked well for it. Each campaign relied on stage design to keep from making passing through the same areas fresh. The thing is, though, even if there are 4 characters there is only 3 different forms of gameplay which are the lead characters, who play the same, and their backups, who have very simple mechanics. There isn't much in the way of variation, just different guns.
And this is RE. They get all of Capcom's money and attention. DMC does not.
The issue with half a dozen characters is a lack of focus, on the both narrative and game design aspects. No one is going to say we just want skins of other characters, either. Yeah, right. They want full blown story campaigns and an entire set moves for them, and who is going to pay to have that made? So what we have is a whole bunch of chunks. Rather than one single defined and tuned experience we have a whole bunch of fragmented little ones that lack on everything. We already saw something like that with DMC4 and SE. Nero is shy on armament, that has always been a complain, he lacks other weapons and moves for them so he can get old fast. Trish doesn't have that much in the way of unique moves; she has pretty a recycled galley and it's kinda messy with moves that you wish were there but aren't.
One character with an outstanding campaign and set up rather than 20 with fragmented ones is the preferred choice for me. More is not better, especially when it means dividing your resources.