I don't think Tri-force has as many wasted stats as you would think Elman.
Sheen procs: If you're building damage Nocturne, think about how many Sheen procs you need to kill a squishy target. Ult -> Q -> E -> W-> Dead? You can very easily get 4 Sheen procs if you time your abilities correctly, and that's basically all you will need in most cases.
Movement speed is also huge on Nocturne, since his only CC is a tether'd ability, requiring him to stay in range, so the phage and passive MS help a lot.
Yeah, the AP may be wasted, but it's wasted on almost everyone who builds it. The mana is really nice especially early game.
Personally, I would never build Hydra on Nocturne. His passive is basically already a Hydra, so having Hydra is just overkill. BOTRK or Tri-force + Brutalizer and then Randuins/Situational tanky.
Ninja Tabi + Ancient Golem should be your go-to in most situations, but Merc Tread and Elder Lizard can also work.