Because as painfully cringy and unfunny the Nostalgia Critic schtick is, there is a market for it.
There is a market for pretentiously smug pseudo intellectual high-school level "analysis" of films which is why Lindsay has gin-money.
I'll throw in a tepid defense of TGWTG here. It was a decent niche at the start, applying an actual critical lens to an era when pop culture exploded into ubiquity. These were people who wasted their college loans on film school and theater, and to be fair they put those useless skills to semi-productive use. People find value in learning how to appreciate things in a different way, and there's value in figuring out why a story bugged you for some reason you can't quite put a finger on.
But there's a difference between critical analysis of structure, plot, story beats, characterization, and yelling HURR DURR DIS DUMB. I stopped watching Channel Awesome one day when I saw the entire front page, every single video, was people just smugly
shitting on things. It wasn't properly critical; the videos were bland, predictable, and puerile... just like the pop culture artifacts they claimed to critique. The genre flamed out once the source materials were picked over and the handful of clever observations had already been made.
To give an example of pop criticism done right, there was a show called Brows Held High by Kyle "Oancitizen" Kallgren. He focused on pretentious art house movies, the kind that film professors and Cannes judges masturbate over and make up sub-sub-genres to classify. He did things like
a review of Gerry (featuring Obscurus Lupa!), which took the most boring film possible, applied high art school critical theory to explain
why it was made intentionally boring... and managed to make it entertaining. His
parody song review of The Man Who Fell To Earth is as close to productive art as you got in this genre.
After a few years he shook up his format and went nuts with SJW nonsense, of course. Almost all of them did. He's now TDS-addled, #resistance, pro-Antifa, with
Twitter bio pronouns, the whole works. Critical theory is a far left cultural tool, and even when they tap down the politics long enough to make entertaining deconstructions of Transformers, the dysfunction it encourages eventually comes out.
TL;DR The fault in the Critic's genre was the fault with critical theory itself: eventually, you have torn down everything around you. Your failure to create meaning makes you bitter, feral; and you turn to destroy anything else you can find.