It's a little funny and a little sad that Hussie has been fighting off this exact bad-faith criticism for over 10 years now lol. To provide another quote on the matter, this one from Formspring all the way back in 2011:

Q: "So I think Equius was way more of an interesting and complex character than you realise. Yes, more than you, the author, realise. I find his death disappointing because I read heaps more into him then you deliberately put there. DEATH OF THE AUTHOR, BITCH"

A: "Oh ok I accidentally made him a complex character?
WHOOPS!!!
Every aspect of him was deliberate. I try to make even marginal characters as interesting as they can be with limited exposure given. But they're still marginal, and he was still fundamentally a gag character in spite of those complexities.
I'm just sort of shaking my head here at anyone crestfallen TO THE MAX about Equius's failure to stake a heroic claim on Homestuck's already IMMENSE plot footprint. Like, seriously? With as big a thing as this story is, people are gonna hold a candle light vigil on my lawn for the GREAT SWAN SONG of the dude whose overwhelming gimmick was fetishistic submission? THERE ARE BIGGER FUCKING FISH TO FRY, PEOPLE."

(archived at https://wheals.github.io/formspring/formspring.html#question158899822194104537)

Not every story is going to be Undertale or Steven Universe, and not every character's growth is going to put them in a "better" spot than they were when they started - if things were that way we'd have no conflict and no villains. What I would ask is: if Hussie really didn't like Equius that much, what's the significance of Equius becoming part of the comic's ultimate, most important villain? I get the impression Hussie actually liked Equius quite a lot! They just liked Equius for different reasons to why you like him; they liked his massive negative potential, as a villain representing the kind of person who ultimately doesn't become a better person despite all opportunities provided for them to do so.