I actually liked Sunshine.
Back to the subject though, if Nintendo failed to release a single open world 3D Mario game for the last 11 years, chances are that they either don't want to make one, they don't sell
or they can't make one in an HD environment. They already stated it pretty clearly that the challenge of HD is a steep hill for them. Maybe Mario's just gotten stale over time?
If the series has gotten stale, it's only because Nintendo let it.
The integrity of the Mario series was overwhelmed by the financial success of NSMB. Yes, no Mario game is at all a bad game, but no Mario game since Galaxy 2 has evoked the same feeling of grandeur, at least with me. But it's because Nintendo's not trying to do that, they just keep trying to squeeze out another cash cow.
With 4 games in the "New" series and barely anything different among them besides new levels and power-ups, it's honestly hard for me to believe that the 3D Mario series is headed in the same direction. 3D Land felt really cheaply made with repetitive level design and questionable technical effort, but I suppose Nintendo were in a crisis to make a Mario to boost sales for the 3DS. 3D World, on the other hand, was a vast improvement, and was the first time I saw hope for Mario's future.
I love 3D World, I'd put it at #4 favourite game, 3rd being Galaxy, 2nd being Galaxy 2, and 1st being 64 (Yes, my top 4 favourite games are 3D Mario's). It's a good start to put Mario back on the high-quality track it deserves but it's already taken a hit, being the lowest selling 3D Mario for its first week, and if the initial reaction of the game's reveal during E3 showed Nintendo anything, it's that this wasn't what many people wanted out of a 3D Mario.
But this can be an opportunity for Nintendo. If you want to win, you have to lose first. Maybe Koizumi's statement about making an open-world Mario should be applied less literally. Maybe Nintendo is hoping to stop playing it so safe with Mario again. 64, Sunshine and Galaxy were pioneers of 3D platforming, despite whether it really worked or not they are the games that will stand out, but 3D Land and 3D World won't because they're just imitators.
Though I still hope that Mario will eventually get the 'open-world platformer' treatment, as long as Nintendo keeps the franchise on the right path I'll be happy.
Just no more "New" games or "3D <blank>" games, mkay Nintendo?