Barrett conceded it was a difficult call but the potential All Blacks opportunities had to take priority.
"It was a tough decision — it is tough for everyone," Barrett told Veitch on Sport on Newstalk ZB.
"That carrot of a gold medal is dangling in front of our faces — although it's not going to be easy, it's going to be very competitive over there in Rio."
"I just want to focus on my 15s game. I think I have got enough to work on. I don't think we can underestimate the importance and the great opportunity of playing for the All Blacks."
In many ways, it's a logical decision. In 2016, for the first time in than a decade, there won't be the giant shadow of Daniel Cater looming over all other contenders for the All Blacks No10 jersey. It's a 'situations vacant' Barrett clearly wants to take advantage of.
"Obviously DC's moving on at the end of this year and it's an opportunity for someone to stand up," he said. "That's a challenge I'm really looking forward to [and] I see my future in the 15s game."
Barrett also needs to become a starting player at international level, rather than the bench roles that have characterised most of his All Blacks career.
Sonny Bill Williams and Liam Messam are believed to be the only two frontline All Blacks who have committed to the 2016 sevens tilt at this stage.
Julian Savea, Victor Vito and Malakai Fekitoa were believed to be also at the top of Tietjens' wishlist, along with Smith and Barrett.
An extended sevens squad will be named after the World Cup, with the 12-man final Olympic team to be announced in June.
Players involved in next year's sevens programme are expected to miss a big part of the Super Rugby season, as well as the three June tests against Wales. They would also be unavailable for part of the Rugby Championship.
