I would argue that several characters have made the main character irrelevant, not that he has become more important.
Made irrilevant because for some reasons the main char has already now , not 1, but maybe 2 Demons (blues and wings) stronger than the supposed "final boss" (neo). This is a char that had a fast, steady growth up until i'd say the gourmet world happened, where suddendly a lot of old "strong chars" were offed up absurdly fast (the supposed 2nd strongest of the I.G.O.? All of a sudden dumb fodder dies in 1 page. All the chefs of the bishokukai that should be stronger than Star? Offed in 3 panels not even a page. Knocking Master Jirou, the arguably strongest man in the world? Offed in one chapter to hype the enemy that we know is still below the demons of the main char).
The manga strenght was its ability to have tons of different characters of different strenght, several eclipising the main, and seeing the main move up slowly the stairs of powers, with good harsh fights and steady poweruppings. Kuromado? Grimmjow? Niceny? Zaus? Mansam? All characters that were hyped a lot and basically were made irrilevant off-page. Now Jirou and soon Midora. Teppei was another that basically disappeared, but is completely irrilevant by now since anything below Midora is useless. There was a sense of wonder of knowing the goals that had to be surpassed, but then? You were always excited to see one of those chars enter the stage, because it made you know that shit was about to get real, and that bloody fights were the main could lose or win were ahead. That excitment is completely gone by now. Char will win and get absurd powerups, like getting 10x times as stronger in the same chapters ***** hell, because the manga has to end fast.
We passed from nuke-level of power to the ability to destroy the earth several times over in what, 100 chapters? What the fuck. The human world was 270 chapters, and the gourmet world, hyped to no end, has basically been skipped and done in 100 chapters. If you want to end it just be done with it, don't ruin it with the worst pacing imaginable. The Human world could've been done easily with 50-60 less chapters, but the Gourmet world absolutely needed more exposure, and many characters needed not to be offed in short panels. There are some good chapters here and there but then sometimes i go read the first arcs, ice hell arc, regal mammoth, the first gourmet world exposure etc... and it feel so fucking bad. Toriko should've had HxH fate of going in permanent hiatus or just interrupted not this torture.
EDIT: not to talk about all the fights with the beasts , the capture levels that gave you all the illusion of a coherent structure. Now even the strongest beast have been made irrilevant and we skipped fights with 4k beasts that were on Jirou's full course and had tons of hype, as well as skipping completely Jirou's full course items like some fodder shit. Not only that but the main protag that was extremely aware of the strenght of his enemies in the beginning (see vs Star GT-robot) is now a dumb idiot that think honestly that can challenge beasts that fodderize him in half a panel only to be saved by a deus ex-machina that at the same time power him up like 20 times.
It's as if i was reading HxH and all of sudden it become Fairy Tail but where all my favorite secondary characters die because the manga has to end fast. It's awful.