The interesting thing is that during EA, a lot of people seemed disattisfied with the good path and felt the good side of things was going underserved - I was one of them in fact. Larian also said that they were presenting the evil companions first because they knew people tend to play the good path in games so they wanted players to try out evil content. They said that explicitly. Apparently whatever they learned from that directed them this way. I also don't think this is the result of them being rushed, at least not rushed in the sense that they absolutely needed more time to finish it. They completely changed Wyll's story and character from Early Access, including I believe hiring a new voice actor. And despite having Karlach apparently planned as part of the game for a good while, they didn't apparently have a handle on her character until they cast her actress (I will say that I adore Karlach, she's my favorite character and I would genuienly have enjoyed the game a lot less if she had remained as she'd been in EA, that's a character I'd have found boring and I think her positivity is exactly what makes her interesting and she's the type of character the story very much needed). They released about three months early, at most? And this is after Covid caused them to have to delay by at minimum a year, maybe two. The problems we see aren't because Larian rushed anything, it's because they used their writing time irresponsibly. They made massive structural changes to the game's story pretty last minute. They should have had the story locked down far sooner than they apparently did. It's not just the lack of evil content that's apparent, I stand by my belief that the entire main plot of the story is a complete mess that's entirely non-functional from the opening cutscene right until the end. They constantly wanted to keep tweaking and adding things when really they should have just accepted what they had for good or for ill and focused on polishing that.
I don't think Larian is trying to punish players for playing evil, at least that's not their driving idea behind evil choices. I just think that they wrote themselves into a corner and couldn't actually manage to pull off what they were trying to do. This game has a lot of little stuff that gets reacted to, and they also wanted to stuff it full of things they thought were cool. They had to include the stuff that was the backbone of the story, and then they had to deal with the heroic path because that's still the path most people take, and then they had to address problems, then they changed things, then they had to actually WRITE Karlach and rewrite Wyll (notice how Karlach especially doesn't even really have a quest, just picking up tow peieces of metal, talk to an npc, then do a thing you were probably already going to do with her in your party and then boom, they're out of time. Oh yeah, and they had to actually ADD content for Halsin and Minthara to make them companions when they were never meant to be that.
So no it's nothing to do with moralizing or teaching anyone a lesson. It's just plain incompetence and poor planning. Nothing more complex than that.