The incentive for 2016 picks over 2015 picks already exists, because we have three 1sts in 2015 already. There's always a preference to spread picks out over drafts when all things are equal. All things aren't equal due to the strength of the 2015 draft, but it's hard to sit here and figure out how you then weigh those two factors. At some point you'd rather have a mid-teens or early-twenties 1st from the weaker draft rather than yet another in 2015.
Stockpiling 1st round picks in ANY draft is never a bad thing though. Case in point: In the 1998 draft, Colorado had 4 first rounders, they took Tanguay, Skoula and Regehr with the first three. Skoula didn't fulfill expectations so I guess the argument could be made that he was a bust, but that's another discussion...
In Hershey (AHL affiliate at the time) they were still trying to develop Wade Belak into a defensemen, but with no other physical presence in the lineup, he became a nightly fighter weather he wanted to be or not (trust me, it was painfull watching how Bob Hartley used Belak in those days) They desperately needed an enforcer, and so Colorado (who were right in the middle of the Detroit rivalry and the McCarty/Lemieux crap was still going on in that prior year) drafted the best fighter in the draft in Scott Parker. People look at that draft now and wonder how the Avs could "waste a pick" on Parker when all those other skilled players were still available.
With draft picks stockpiled, they were able to fill a very specific need that they had in the organization. It didn't hurt that the guy had just put up 30G's and 22A's the previous season in the WHL. Offensive potential on the 4th line was a plus, and that's why they drafted him, he just pounded people to death and that's what they needed.
So stockpiling inside one draft isn't necessarily a bad thing, more options are good in any draft.