You're not missing anything—that's just how Smithing is balanced in vanilla. The perk tree front-loads the payoff because once you hit Daedric or Dragon Armor, the gear scaling flattens out hard. The perks aren't really a trap so much as they're done doing their job once you unlock the top-tier recipes.
That said, there's two things that actually matter past level 30:
First, the Improvement side of Smithing. Perks like Arcane Blacksmith (lets you improve enchanted gear) and the ones that boost your improvement damage actually keep scaling. If you're on Adept, you probably won't notice, but that's where Smithing stays relevant—keeping your current gear ahead of what you find. A lot of people sleep on this because they assume better gear = loot from dungeons, but crafted and improved gear can outpace that.
Second, if you're bored with the perk investment, you could just... not do it. Grab Steel Smithing early, then pivot hard into something else. Smithing is one of those skills where you can get like 70% of the value from 20% of the perks, and the rest is just QoL. Your third playthrough is the perfect time to try a different approach entirely.
If you ever jump to PC though, Ordinator completely reworks the Smithing tree to have late-game utility—stuff that actually scales with your character level. Makes the whole skill feel less one-note. But on vanilla SE, yeah, you're hitting the skill ceiling real fast.
