Take more time? In october the WiiU is out for almost a year. It needs a game like 3D Mario for christmas.

Mario Galaxy (developed by Nintendo EAD Tokyo1)was also out within Wii's first year.  
You can be pretty sure that WiiU Mario development began right after Mario Galaxy 1 was completed. Galaxy1 is actually the last thing that took effort to develop that was made by EAD Tokyo1  since stuff like OOT 3Ds which is just a "remake" and even was co-developed by Grezzo shouldn't take much time/manpower. (the game was basically there they just had to add some stuff and change some code etc and I bet Nintendo was just supervising)
And the last thing ever thatwas made by EAD Tokyo1 was the Legend of Zelda Four Swords Anniversary Edition which was out September 2011 (and this was also codeveloped by Grezzo) And I doubt they didnt do anything at all since 2011.

And Mario Galaxy 2 (if it would have been made by EAD Tokyo1) obviously  wouldn't have taken the whole team to develop since it is "based" on Mario Galaxy 1's idea and engine . But good for us it was made by a completely different team  EAD Tokyo2. So EAD Tokyo1 was not involved at all and had time for WiiU Mario.

And since Mario 3D Land (also made by EAD Tokyo2) was completed 2 years ago (when this october arrives) We now could have  both teams working on the new WiiU Mario for 2 years to finish what EAD Tokyo1 might have started in 2007. 

The only problem I see is that Wikipedia lists EADTokyo2  as the developer for WiiU Mario.
So in the worst case scenario we have just Tokyo2 working on the game for about 2 years now. And the best thing that could happen is that EAD Tokyo1+2 are working on it and development started 6 years ago.

But I am pretty sure if EADTokyo2 is the "developer" it just means its the main developer it doesn't exclude Tokyo1 from assisting (Monolith Soft and Retro are not listed as co-developers of Skyward Sword and Mario Kart7 and we know they were assisting!!!)


Conclusion:
Nintendo is making their first HD Mario they will make sure to impress us. Mario games always had good gameplay and Mario Galaxy a year 1 Wii game visually impressed everyone.  EAD Tokyo2 was able to make Mario 3D Land in roughly 1.5 years and it turned out to be a great game.PLUS Nintendo said they pushed back release dates to make great games! So don't worry!

Alongside a cut and MK Wii U, this will work winders.

Looks like good news for the Wii U finally !

So far so good. Enjoying everything except the motion controlled levels like that stingray water race one. I would've probably enjoyed it back in 2007, but in 2013, not so much. Other than that I can't complain about anything else.

Cool, i hope to see a new Donkey Kong later on at some point too

I don't think they are going to cut the price , but will instead bundle games like crazy. I fully expect MK to be bundled with the Deluxe when it launches. Rumor is they are bundling NintendoLand with the basic version too.

I kind of don't see most of this as surprising considering Iwata has said several times that they were planning to release software in the second half of the year, and with the goal of having 100bn yen in operating profit, they would need to have a ton of games ready. The whole advertising bit makes sense too....why throw tons of money at advertising when nothing was coming out for the system and when it wouldn't see dividends from the ads until the next fiscal year? There are several games releasing this month, VC releases weekly (even if it is only 2 a week), and soon they will roll out one of there "several Nintendo Directs leading up to E3" which will likely begin the hype train. They have sold about half as many Wii U's in 4.5 months as Microsoft sold 360's in the first year, so they could easily have a similar, if not larger lead by the time the PS4/720 launch. 

The Mario game will absolutely be ready this fall and I can see October as well. The Mario 3D land team was likely smaller than all of Tokyo Dev 2 seeing as they worked with 2 other smaller dev teams. The majority of people were working on this. Pikmin was delayed likely because the team was split between NSMB2, NSMBU, NSLU, NSMB2 DLC and Pikmin.....that's pretty well spread thin if you ask me. Retro's game was supposedly supposed to be shown at last years E3 so I expect it will be ready by Christmas, and no...they haven't been working on Mario Kart. The hires they have made all have some pretty wicked backgrounds in terms of tone. They also developed their own engine that puts out visuals above Killzone 3 and runs at 60fps according to rumor. Even if it doesn't do exactly that....it's still going to be gorgeous.

Exciting times.

The answer to a system that isn't selling with a Mario game ... is more Mario games. 

Granted I do think Wii U sales will improve because they simply can't be any worse, but I have to wonder if Nintendo is largely just trying to appeal to the same audience here over and over again.

Wii Sports is what brought a true broad audience in to the Wii, everything else IMO piggy-backed off that.