I can confirm that the game got a T on its own merits. No censorship. The game simply isn't as "lascivious" as people seem to imagine it to be.
As for why we went with Burst as opposed to Shinovi Versus... Well, for starters, Senran Kagura (Burst) is the start of the story. It's the origin of the franchise, and contains all the backstory elements for all the Hanzo and Hebijo characters, which Shinovi Versus largely glosses over. While Shinovi Versus does tell a standalone story, it assumes players already know what happened in Burst, and players who are already familiar with Burst will definitely get a lot more out of Shinovi Versus. Therefore, if we're to introduce the franchise to North America, the 3DS title is the logical choice, since it is the very beginning.
Also, gameplay-wise, Burst and Shinovi Versus honestly aren't THAT different from one another. People seem to assume they're like night and day, and while they certainly do have some very notable mechanical differences, they're structured nearly identically, with the only major difference being the ability to control the camera directly during stages in Shinovi Versus, as opposed to the fixed camera perspective in Burst. And... because of this, I actually kind of prefer Burst, personally, since you never have to worry about mucking with camera views! Feels more like a classic brawler as a result, which I generally prefer to 3D brawlers. But, your mileage may vary.
Either way, SKB is a great game, and I urge those who are only buying into the "it has boobs lol!" gimmick to give it a more serious look. It's a genuinely fun brawler with a surprisingly dark story, cool move sets and likable characters. It is indeed designed to sell on its T&A factor, but fortunately, there's a lot more depth to it than you might initially expect, and a lot more to love than simply the shape of the characters' bodies.