I always hear on NeoGAF and a ton of other gaming circles that the Wii U was underpowered and that the hardware wasn't good enough for 3rd parties to develop for. Only recently has the hardware made a huge difference because there's no reason why any of these titles couldn't have been playable on the Wii U:
2013:
DmC: Devil May Cry
Metal Gear Rising: Revengeance
Naruto Shippuden: Ultimate Ninja Storm 3
Tomb Raider
BioShock Infinite
Metro: Last Light
Grid 2
The Elder Scrolls V: Skyrim – Legendary Edition
Saints Row IV
Madden NFL 25
Dead or Alive 5 Ultimate
Injustice: Gods Among Us Ultimate Edition
Grand Theft Auto V
2014:
Thief
South Park: The Stick of Truth
Metal Gear Solid V: Ground Zeroes
Wolfenstein: The New Order
Grid Autosport
Ultra Street Fighter IV
Destiny
Naruto Shippuden: Ultimate Ninja Storm Revolution
Persona 4 Arena Ultimax
Alien: Isolation
Borderlands: The Pre-Sequel
Assassin's Creed Rogue
Call of Duty: Advanced Warfare
2015:
Resident Evil: Remastered
Saints Row: Gat out of Hell
Life Is Strange
Dragon Ball Xenoverse
Resident Evil: Revelations 2
Metal Gear Solid V: The Phantom Pain
Call of Duty: Black Ops III
Not to mention the various annual sports titles that missed the system almost completely like FIFA, Madden & 2K. The excuse that "these series hasn't been on Nintendo platforms before" can be seen as positives for them to be released on Nintendo systems. Dead or Alive, Grand Theft Auto, Resident Evil, Call of Duty, Dragon Ball Z, Metal Gear Solid, Street Fighter were all series that had key games on Nintendo consoles and handhelds. Publisher's could have tried to grow the fanbase that was established on earlier Nintendo consoles with these series and help that Nintendo fanbase for those series grow.
On top of that games like Injustice: Gods Among Us Ultimate Edition, The Elder Scrolls V: Skyrim – Legendary Edition, Ultra Street Fighter IV, Persona 4 Arena Ultimax were all the "complete" versions of those respected series so it would have made logical sense to market to a demographic that could easily jump into the series and perhaps purchase newer games in the future.
Some 3rd party publishers outright screwed Nintendo over (Ubisoft, Sega, EA) when it came to the Wii U causing great disparity between Nintendo and other 3rd party publishers. What if Ubisoft keep true to their porting decisions by holding the release of Watch Dogs until the Wii U version was finished like they had held the Wii U version of Rayman Legends until the Xbox 360/Playstation 3 version were finished. For that matter what if Rayman Legends stayed an exclusive? What if Sega didn't do the bare minimal for the 3 Sonic game deal and actually produce new Sonic games and not slap a game that was never attended for the system (Sonic Boom) and a game they were going to develop for Nintendo regardless of a deal (Sonic & Mario at the Olympic Games). What if EA published the Mass Effect Trilogy on Wii U rather than JUST Mass Effect 3.
Instead from some of the same publishers of the games above low quality, low effort software was ported to the Wii U rather than their big core franchises like: The Amazing Spider-Man, Hot Wheels: World's Best Driver, Wipeout: Create & Crash, SpongeBob SquarePants: Plankton's Robotic Revenge, Cabela's Big Game Hunter: Pro Hunts, Transformers: Rise of the Dark Spark, Pac-Man and the Ghostly Adventures, The Peanuts Movie: Snoopy's Grand Adventure. A bunch of these titles were no more than quick cash grabs while the big AAA titles went to Sony, Microsoft and PC. The hardware was competent enough to handle a large number of titles so the Wii U being "underpowered" never should have been an excuse to begin with. At this point I'd just want publishers to be up front and say "We don't support Nintendo consoles because XYZ" instead of talking around the issues saying crap like "We'll see if the platform makes sense" or "Wii U version is always a possibility".
tl;dr Hardware wasn't an issue for a lot of titles for the Wii U, the 3rd parties were.
2013:
DmC: Devil May Cry
Metal Gear Rising: Revengeance
Naruto Shippuden: Ultimate Ninja Storm 3
Tomb Raider
BioShock Infinite
Metro: Last Light
Grid 2
The Elder Scrolls V: Skyrim – Legendary Edition
Saints Row IV
Madden NFL 25
Dead or Alive 5 Ultimate
Injustice: Gods Among Us Ultimate Edition
Grand Theft Auto V
2014:
Thief
South Park: The Stick of Truth
Metal Gear Solid V: Ground Zeroes
Wolfenstein: The New Order
Grid Autosport
Ultra Street Fighter IV
Destiny
Naruto Shippuden: Ultimate Ninja Storm Revolution
Persona 4 Arena Ultimax
Alien: Isolation
Borderlands: The Pre-Sequel
Assassin's Creed Rogue
Call of Duty: Advanced Warfare
2015:
Resident Evil: Remastered
Saints Row: Gat out of Hell
Life Is Strange
Dragon Ball Xenoverse
Resident Evil: Revelations 2
Metal Gear Solid V: The Phantom Pain
Call of Duty: Black Ops III
Not to mention the various annual sports titles that missed the system almost completely like FIFA, Madden & 2K. The excuse that "these series hasn't been on Nintendo platforms before" can be seen as positives for them to be released on Nintendo systems. Dead or Alive, Grand Theft Auto, Resident Evil, Call of Duty, Dragon Ball Z, Metal Gear Solid, Street Fighter were all series that had key games on Nintendo consoles and handhelds. Publisher's could have tried to grow the fanbase that was established on earlier Nintendo consoles with these series and help that Nintendo fanbase for those series grow.
On top of that games like Injustice: Gods Among Us Ultimate Edition, The Elder Scrolls V: Skyrim – Legendary Edition, Ultra Street Fighter IV, Persona 4 Arena Ultimax were all the "complete" versions of those respected series so it would have made logical sense to market to a demographic that could easily jump into the series and perhaps purchase newer games in the future.
Some 3rd party publishers outright screwed Nintendo over (Ubisoft, Sega, EA) when it came to the Wii U causing great disparity between Nintendo and other 3rd party publishers. What if Ubisoft keep true to their porting decisions by holding the release of Watch Dogs until the Wii U version was finished like they had held the Wii U version of Rayman Legends until the Xbox 360/Playstation 3 version were finished. For that matter what if Rayman Legends stayed an exclusive? What if Sega didn't do the bare minimal for the 3 Sonic game deal and actually produce new Sonic games and not slap a game that was never attended for the system (Sonic Boom) and a game they were going to develop for Nintendo regardless of a deal (Sonic & Mario at the Olympic Games). What if EA published the Mass Effect Trilogy on Wii U rather than JUST Mass Effect 3.
Instead from some of the same publishers of the games above low quality, low effort software was ported to the Wii U rather than their big core franchises like: The Amazing Spider-Man, Hot Wheels: World's Best Driver, Wipeout: Create & Crash, SpongeBob SquarePants: Plankton's Robotic Revenge, Cabela's Big Game Hunter: Pro Hunts, Transformers: Rise of the Dark Spark, Pac-Man and the Ghostly Adventures, The Peanuts Movie: Snoopy's Grand Adventure. A bunch of these titles were no more than quick cash grabs while the big AAA titles went to Sony, Microsoft and PC. The hardware was competent enough to handle a large number of titles so the Wii U being "underpowered" never should have been an excuse to begin with. At this point I'd just want publishers to be up front and say "We don't support Nintendo consoles because XYZ" instead of talking around the issues saying crap like "We'll see if the platform makes sense" or "Wii U version is always a possibility".
tl;dr Hardware wasn't an issue for a lot of titles for the Wii U, the 3rd parties were.