I love creators who integrate voice acting. It really helps to set the atmosphere and realism of the porn. However, I do have a bit of constructive criticism. One thing I find distracting in animations with voice acting is this sort of unnaturally-wordy, almost clinical-sounding speech. Like, instead of someone saying "Yeah! Just like that," or "Yes, that's where I want it," they'll say things like "Yes! Stick your big penis inside my vagina you big strong man!" It often takes people out of it unfortunately

(Content warning: incest, rape) The problem can be exacerbated by the presence of this type of dialogue in more intense porn. It can be extremely distracting when the dialogue, rather than something like simply, "yes mommy" goes like "Yes mother, suck your son's big blue cock!" or instead of, for example, a mere "you're mine now," goes with "I want to rape you now! Sit still while I tie you up, you helpless cat!"

Absolutely no disrespect to the voice actors or the animators, but this type of writing is unnatural-sounding and it sometimes causes users to just close the video. I know it's furry porn and therefore always fictional, but dialogue that doesn't sound at least somewhat based in realism just throws cold water on the viewing experience sometimes. I would recommend instead using dialogue that's as natural as possible.

Does anyone else experience this?

isn't this a problem with porn as a whole?
stiff porn dialogue is a well known cliche

Depends on the specifics.

Some of it makes sense to me. Like that incest example of yours, since the dialogue focuses on the fetish itself.
But the whole " Stick your big penis inside my vagina " doesn't sit well with me. Though that's less about the literalness and more about the wording.

Overall, I guess I'm neutral about it

Overly literal dialogue just sound fake to me, almost as if you're trying to fake an orgasm.
I prefer either very subtle/suggestive dialogue that leaves much up to the interpretation of viewers, or genuine expressions that people would actually say.

It sounds to me like you just don't care for dirty talk? I think the unnaturalness, to an extent, is part of the appeal exactly because it doesn't sound like something people would normally say. It gives the impression that the character is so horny that they've lost all care for coming off as modest or civilized and are just stating their prurient desires out loud. There are certainly more and less skillful ways to write it and deliver it, but I think effective dirty talk should make you think "wow, I can't beleive someone just said that...".
The only fundamentally bad line among your examples, in my opinion, is the rape one. It tells rather than shows, (just draw or animate the victim being tied up) it focuses on the wrong things (we can infer that someone is going to be raped, why not let the rapist describe how exactly their gonna do it if you need them to speak?) And the phrases "I want to rape you now" and "you helpless cat" are so stilted and awkward that they would just make me question if the writer is a native english speaker, which could break my immersion.