Over seven years ago, this has been foretold exactly by the show Silicon Valley:

https://www.youtube.com/watch?v=K3pYZwol6Dc&t=73s

Transcript of the fridge scene:

    Fridge (after a bar code was scanned): "Ah, there we go."
    Gilfoyle: "It's bad enough that it has to talk. Does it need fake vocal ticks like 'uh'." 
    Dinesh: "Well it just makes it sound more human."
    Gilfoyle: "Humans are shit. This thing is addressing problems that don't exist. It's solutionism at its worst. We are dumbing down machines that are inherently superior."

I would like to have a Gilfyole mode for NotebookLM where the machine answers only with cold precision instead of endless "Mmmhmm", "Yeah!", "Amazing!", "That's so cool!".

Absolutely the same complaint. I wanted to see if it could summarize papers well, but I just could not handle all the conversation and attempts to make it 'exciting'. Especially in areas where I already know the background.

It's one of those things that's impressive initially, but after generating a couple it feels quite formulaic.

I really is an obnoxious level of over-enthusiasm.

Give German a try - trust me, you don't have to speak the language but anyone can tell that it's quite different in tone. No valley girls in Deutschland!