From everything I've witnessed so far, the degeneracy has been vastly blown out of proportion and you'd essentially have to be trying to seek it out to witness it.
But yeah, you'd miss out on companion quests and their occasional input in conversations if you don't take them. I'm sure there is plenty of content in the game anyway, so just ditch them if you don't think you'll be able to avoid things you don't want to see.
No, it's very real and very omnipresent, BUT (mainly)
only in the conversations at camp. As myself and several others have said, being in camp you're frequently confronted with sluttiness/faggotry and looking for conversation options that don't "advance the adult romance" is sometimes like looking for a needle in a haystack, and when you do find it (by adroitly avoiding, like a fucking ninja, all the options that you can just smell are leading to romance/sex-furthering), the choice of avoiding all that shit makes you look like an asshole.
For example, at one point Gale is pissing about with magic (an image of Mystra he's conjured) and he starts waxing eloquent about the intoxicating beauty of the Weave and invites you to try contacting the Weave yourself. There's a charming sequence with some skill checks where you fumblingly try to do emulate him conjuring something weave-y, then you succeed, but then there's a faggot moment where Gale gets close, your two characters are repulsively animated like two faggots smiling and making sheeps' eyes at each other, and then two of the subsequent conversation choices lead to faggot shit in one way or another, with the remaining option being to brutally close the interaction. There's no option where you can be charmed and intrigued by the magic and terminate the experiment in a pleasant bro-like fashion, thanking Gale for the experience, without him sticking his tongue down your throat. This sequence might have worked for a female character (although what are you doing, doing romance as a female character if you're a male player lol), but it's quite jarring the way it's set up - presumably as a "teaching moment" to teach you that "love is love" don't you know. It's quite disgusting.
[Later note: silly me, I realized a few further posts down what it is. The sequence was obviously designed for a female player character and Larian were too lazy to change it appropriately for a male - and being conformist to woke crap
afforded them that laziness, and they probably thought it was funny.]
Now you could say, "you don't have to do
any of that," and you'd be right. But it could have been alright as a sequence just with a pleasant termination as an option, it's just that the game makes you seem like a Trump supporter for missing out on the teaching moment. While "romance" in CRPGs is a dubious proposition unless very carefully handled (as someone said above, as in BG, where the romance unfolds very gradually from casual to deeper conversations), building relationships in CRPGs can be a good thing, and it widens the
gesamtkunstwerk of the CRPG if you have them. But this game canalizes that desire for richer imaginary relationships with your imaginary friends into you being taught to "tolerate" degeneracy.
So yeah, while you can handle the game without any of it, and the combat and exploration are pretty good overall, this (as I've called it) Loverslab Lite approach to the companions is really annoying.