Putting points into speech and auto winning in conversations isn't very compelling gameplay, if it's gameplay at all. Planescape Torment has more advanced, complex conversations which is a step in the right direction. But to use your example with Chavez, you can indeed headshot him with a single button press. Or melee him. Or shoot him up close. Or throw grenades at him. There's far more options in combat than speech.
Absolutely agreed with the bolded, and that is a problem, yeah. There's no reason to keep making conversations just "select a sentence in a completely static manner" when we made almost everything else into a complex puzzle, a constant reflex check or an activity with plenty of flow
- Trauma Center; Papers, Please; Car Mechanic; Octodad; Katamari; Phoenix Wright; etc. It's fucking telling that the most compelling/unique mechanical change some games did to spice "selecting a sentence" is... adding a time limit while to try to find the "right" answer.
While I was very much impressed with how Deus Ex Human Revolution did dialogue, and Black Isle/Interplay/Obsidian also does some good stuff, I think that's a problematic point. In combat, there's always one goal: deplete the enemies' hit gauge before yours is emptied. There's multiple ways - or at least different decisions during the course of the combat - to achieve said goal. But dialogue, realistically, has no clear goal or a right answer, and thus games try to reduce it to a win/loss state that needs to be super obvious or the players get confused/lost/angry at it/etc. Also telling how almost no game has conversation systems between more than two characters because of that.
It's the reason I like how Danganronpa does it. Not only all the minigames and zanyness of the dialogue during the jury segments are super fun and fit the overall narrative and aesthetics to a t, it compels me to think about words and replies in a bunch of different, urgent ways. If I'm screaming over someone, I'm not slowly picking a sentence over a list that goes from "Sure, I'll help you" to "No, and give me your money" - I'm fucking putting a bullet through their words with my own. If I'm trying to rationalize a bunch of discussion between a dozen people, mixing lies and speculation, yeah, it's kinda like playing DDR or Tetris at a highspeed, sure. But it also works because I'm rarely just trying to find the sequence of pre made sentences that say "Hey give me an alliance and better equipment" in a pseudo roleplay way - in Danganronpa I'm
trying to discover what has to be said at all
and how to say it
and to whom say it.
Very much disagree with the italicized though. Sure, a lot of games do simple binary/boolean checks where the player doesn't even see it or has any participation on said check/roll, but that is hardly a flaw of "putting points into speech". Choosing to spend resources that grow your character into a better talker, even if completely passive, is decision making with risk/reward and requires knowledge of the game rules - not to mention it potentially enhances the narrative/worldbuilding aspect of the game, either for for pure RP purposes or for adding some personality/character to your character (like the backgrounds in Shadowrun).
That, of course, is not compelling if the game has a skewed ratio of speech vs combat/stealth/hacking/lockpicking/whatever and/or allows you to be uber powerful and a master of both, but that's not an inherent problem with speech checks.
(Sorry if this sounds a bit aggressive, too much of a ramble or unclear, always have a hard time elaborating ideas in English)