When it comes to the roster they have, they genuinely don't need it for a couple of PPVs and other people have either moved beyond Nexus, like Daniel Bryan in the terms of success, Bray Wyatt in terms of character (and success I guess), Justin Gabriel in the sense he's focused on the independent scene, and even Heath Slater in that he won't be taken seriously beyond a mid-card role again. Ryback is also on the outs with the company and whines and moans about it all the time on a podcast. Then David Otunga is stuck on pre-shows and nobody wants to see him wrestle really. Curtis Axel is under a new name and identity and once again is a lower-card jobber. Mason Ryan isn't someone fans are pining to see. Darren Young was just released, nobody has heard from Michael Tarver beyond "hey he's in the indies." Bray Wyatt is in canon not the same as Husky Harris.
They don't need to resurrect a faction from the dead which was kind of a fail in the end (I mean, a tragic story for them and they could have and should have worked, but still failed).