obviously it would help and not hurt to have some more mature IP's butttttttttttt the question is would it be worth the investment of probably a billion or a few billion in $$$$ (not up to date on what Capcom's valued at)
for me personally I do enjoy the Resident Evil series (despite it being terribly lame and FPS like rather than survival horror). they could fix that easily though, Nintendo isn't stupid. also like others mention, DMC could easily be done, Nintendo can do any genre if they just hire the right people (and they tend to do that). Mega Man could be revived
it would be exciting but, again, a bit investment and unlikely to happen. as it stands Nintendo is very conservative financially and does not like to take big risks and investments. there was a million opportunities in the past to bid or buy smaller game and software companies (cough Rare) but Nintendo seems to be comfortable with their own IPs and (I would guess) possibly afraid of what would happen if they acquired too many and were spread too thin. I mean, after all, what's the point of buying out a company with a bunch of IPs if you don't have the time or manpower to develop the franchises and really take advantage of them. that's the one thing with NIntendo, they certainl aren't lacking a multitude of IP's and brands to work with (hence the underuse of things like Star Fox, F-Zero, Earthbound, etc.)
all the same I do think it might be wise for them to buy out a moderately sized successful mature game software developer at some point. it could pay dividends to do so. and by mature, I mean a software company that specifically develops more adult oriented games, whether RPG or action/horror