As far as i know, Sakurai had pretty much free hands with Brawl, since Iwata went and announced the game before it was even planned (well, he didn't announce it, but the press read it as announcement). Including the online (where the problem seems to be the low latency network).
Nintendo did build the online service pretty much out of nothing, people just tend to forget that Live had the same complaints as Nintendo is having now, just that M$ never had the same problem with traffic as Nintendo has.
Why not buy the Conduit IP, why not buy Resident Evil IP, why not buy CoD IP, why not buy any third party IP. Nintendo could afford them.
Why not hire F5 devs or buy Sega or buy a dozen dev studios. Nintendo could afford them.
Just because someone thinks an investment is good or that it would be cool for Nintendo to do something, doesn't mean that something actually is. You can profit only if you make good investments.
There are RPG:s. MMORPG:s are very expensive to maintain. Besides, wasn't the complaint about online, that it's bad. Shouldn't Nintendo focus on making the online work better instead of building an MMO and put more traffic for the servers.
Nintendos profits go to:
Bank.
Taxes.
Shareholders.
R&D.
Other investments (shares, monetary funds).