I voted A, that is the 1st fault.
A: Not enough games to grab interest of anyone, when they add more Nintendo games later it will grab Nintendo fans, but no consoles survives just on hardcore 1st party fans...they need more exclusives like Lego and more 3rd party multiplatforms that launch at the same time.
B: I don't think it's too expensive in itself, but many wonder why buy a new console with little games for $350 when I can get an old console with a lot more games for much less.
C: Its power is low, but I don't think a large amount of people care about that in itself, it's the fact 3rd party would rather work with either established hardware or better hardware.
D: Initially I liked the tablet, and it has perks, but the commercials portray it as a big controlller blocking the way of the TV instead, making it look annoying to core gamers, and its gimmick isn't as cool as motion...making casuals not as interested.
E: There is nothing wrong with trying to cater to everyone, but the Wii U doesn't seem to be catering to anyone...not a lot of core games, not very casual, barely even Nintendoie (3ds has better variety of Nintendo games, and actually has several games with known dates coming this year while Wii U only has 1 Nintendo game that is positively coming this year, Pikmin).
F: I've never seen advertising of the Wii U outside of ones I've specifically looked up on youtube or were shown on gaming sites (by posters not actual ad), so this is a huge problem.
G: I don't think these things are doing anything. It's odd but core gamers seem to state this as a problem for casuals, but I've never heard a casual even remotely consider this type of gaming as the same thing...it's a delusional belief.