Rayman Legends is solely because of the multiplatform release, and nothing to do with any development issues. Speaking to Digital Spy, the publisher explicitly stated the only reason for the new September release window is the additional platforms of Xbox 360 and PS3.
"We usually release all of our platforms simultaneously (aside from PC)," an Ubisoft rep told Digital Spy. "We've made special exception sometimes in the past but it's definitely just on a case by case basis and not our standard practice. I know it's not an elaborate, 'convincing' answer, but it's the simple truth."
In short, the game could have come out when it was originally intended to, which was February 26 in North America. Ubisoft simply chose not to do that. However, if you think Wii U owners are dismayed by the news, imagine how the developers behind the game feel.
That's the message imparted to fans by someone believed to be an Ubisoft employee on Spanish forum EOL. As translated by NeoGAF, the employee, who apparently has a history of posting about his work at Ubisoft on the forum, said it was hard to swallow working so hard over six months and barely seeing family and friends, all to ensure the game came out on time, only to find out about the delay. He asked fans not to turn their backs on the game or the team behind it because "some men in ties one day took a wrong choice." His full post reads:
"I completely understand you but you have to understand one thing. This is not a decision taken by the development team, this comes from really really high up, so please don't pick on the game. If you're pissed, imagine how we feel. Think on the situation, we've been making overtime with this game practically since May preparing E3, and then almost a demo per month (gamescom, Wii U presentation, shops, eShop, etc...) and at the same time trying to actually finish the game. We had a first delay because it was obvious we couldn't finish on time but we gave it all to be there on February. What face do you think we had when the week we had to close the game we're being told it's not going to be released? I couldn't believe it. For practical matters, you'll have to wait for some months for the game to be released and will most likely serve for more content to be added and do it better. For us, this means we've spent 6 months barely seeing our wives, kids, and friends for nothing because, after all, such haste wasn't needed. Believe it, it was a hell to swallow these news. Even then I'm firm in what I said back in the day, Rayman Legends is an excellent game and will still be, and the team that's making it doesn't deserve to have your back turned on them just because some men in ties one day took a wrong choice. This industry is really that shitty."