SMSunshine might have been a disappointment to some, but it certainly did its share of work as far as the IP is concerned. Luigi's Mansion started the 3D update, but SMS finished the job by having a full Mario, Bowser, Peach, Toads, and other essential cast fully fleshed out instead of remaining their SM64 polygon counterparts. The same basic models are updated and used in spinoffs and SMG from there on out. SMS also has elements from it in MK:DD, MKDS, SSBB, PM2:TTYD, etc.
Now as for NSMBWii, let me see if I can't recall all, that's right, all, of the influences it has from previous games:
SMB1: Flagpoles, "Sky" bonus levels, underground levels and BGM, hidden vines, boss Switch, some songs and sound effects (fireballs), Koopas not knocked out of shells, Infinite Lives/flagpole trick
SMB2: Toad, POW Block, Carrying items
SMB3: Items on World Map/No in-stage hold, Airships, Koopaling First Fight theme, various enemies, World Map enemy fights, Anchor, songs
SMW: Yoshi, Secret goals, Single checkpoints w/ Mushroom Boost if Regular Mario, Back Door to Ludwig's castle, select enemies and gimmicks (i.e. Chainlink Climbing), World 9 acts like a hybrid of Star Road/Special Zone, block Switch, Koopa Clown Car, Hot Air Balloons
SMW2: Kamek's power boosts, Yoshi Fluttering, Ground pound wave-generating floors
SM64: Select songs (Freeing Toad in the World Map enemy fights), some sound effects (Warp Cannon aiming, Chain Chomp bark, etc.), Koopa Keys, Bowser face on life lost, Wall Kick/Ground Pound/Triple Jump
SMA4: Hint Videos
MK: Rainbow Road-themed World 9 BGM
NSMB: Enemy/music sync, Star Rank/completion, graphical style, hidden areas shown by see-through element, overall stage aesthetics and structure, Star Coins, Warp Cannons, powerups, anything else really
It's one thing for the series to build upon itself, but I think seeing this level of borrowing a third time after NSMB already did so would be very dangerous to the IP's health as far as "going stale".
I can intentionally throw Ninja Lou-igi into a pool of purplicious poison.
This is the greatest Mario game ever.
Strangely enough, I never fell into the poison. Lava, bottomless sky, yeah, but no death by spikes, poison, or electrocution.
And I got my dad to play from the start to W1 Fortress.
...let's just say that picking him up REALLY sped us up.