I think there's something to be said for the idea that Hussie sets up all these couples, never shows them interacting, and then sinks them as a jab against the fanbase. :P (Or maybe he feels that actual romantic interaction is best left to the hands of fanficcers, since they will write about it themselves anyway? That kind of reflects a... deep and fundamental misunderstanding of what drives people to ship, but Hussie has never understood his fandom.)
At any rate--I don't like how static the characters all seem to be. Part of this owes to character bloat, since half of the characters are one-note gags that Hussie couldn't afford to develop even if he gave enough of a damn about them to want to. But even characters like Vriska, or Dave, whom Hussie ostensibly loves, never seem fully dynamic--Vriska had a full-blown arc with a neat resolution, but now she's back up to her old tricks, seemingly not having learned anything from her past deeds. Dave as well had a pretty neatly outlined arc about confronting his own mortality that resolved after he godtiered at the Green Sun, but during the meteor road trip he's back to dithering and fretting about his Ultimate Destiny as the slayer apparent of the comic's big bad. The characters never seem to change, or in Vriska's case to be capable of changing. (Maybe this is just because Hussie can neither kill nor stop nursing his darlings.)
I kind of think part of this owes to a sense of predestination that underpins the whole comic. A lot of characters' moralities are extremely black and white; they are telegraphed as heroic or villainous--villainous characters are never given the chance for redemption, and heroic characters will probably never fall from grace no matter how far they slide into moral grayness. (Vriska is quite firmly morally gray, but she will never get to escape her non-alignment either--recent updates hammer you over the head with this pretty thoroughly.) For people who are invested in certain characters and enjoy the idea of perhaps redeeming villainous ones (Vriska, Gamzee, Eridan... Caliborn), the canon will just disappoint them, because Homestuck's cosmology makes it clear that what you are is ingrained in you from birth and can never change. In order to change yourself as a person you have to have the free will to change, and paradox space doesn't allow for free will. If you err from the alpha timeline, you will be culled for your choices. On a meta level that seems almost like a slap in the face--"ha ha, the Vriska in your fanfictions who turns over a new leaf and changes her ways just gets all her friends killed for her efforts! Eat it, nerds."
Me, I just don't like determinist narratives in general. I find them hopelessly depressing, and would prefer a story about waging war against fate over one about letting it oppress you. Of course, maybe I'm asking for Homestuck to be an entirely different comic! But I remember very early in the comic's lifespan a time when the fandom actually thought the kids would throw off the chains of destiny(/SBurb, since for awhile people thought SBurb was the "villain") in the end. I wonder if any of those people are still reading now.
I have other problems with the comic but I've ranted enough as it is. Nobody likes a Negative Nancy.