Curse Voice and 3rd Party Programs

The main thing I have to say, though, is that league isn't necessarily the same as other games in terms of playerbase. It's a much more widespread game with a wider range of audiences. In all the online games I've played, league is distinct in its ability to constantly amaze me with the level of douchebaggery and disrespect. That problem has only gotten worse as time has passed. League players in general are getting more toxic, and those who aren't are getting complacent and stop caring. The trolls who will use it will use it to scare off the ones that do. It's not that muting won't solve the problem, it's that muting will give people another reason to alienate their teammates. Teams shouldn't be given further reasons to have to ignore 1/5+ of their team. And outright ignoring those trolls will only make them troll more.
And for the record, I'm pretty sure 1 game out of the last 20 I've played of Dota 2 ended in a 5v5. I don't think that's a perfect example when people in Dota are even more notorious for giving up on games.

And the only reason not many people are using CV is because it's only like a few days old, and the only people who have it are the ones who got keys. The fact that I can hear a subscriber noise go off on a twitch stream like 30 times in less than a minute is rather indicative of the fact that people want it, and when it goes open source people will get it and it will become more widespread.
People want it because it makes the game easier for them. No 3rd party program should ever work that way.
"But people can time their own buffs!" Yes, they can. But no, they don't. People are lazy, don't care, or forget. Giving people free timers for things is rewarding laziness when it should be something they're doing of their own volition. Everyone's acting as if the timers aren't important because people do it regardless, but they don't. I RARELY see anyone who does in Diamond, even. And this feature isn't a non-factor, people are getting it specifically for this.

You're specifically saying that not everyone's going to use it, and that it will make timers and communication faster - ergo making the game easier in more than one aspect. In my opinion, mechanical skill and intuition are two parts of the coin of skill. Taking out intuition is taking out part of half of the players' skill.

but to the vast majority there's no point in winning by cheating.

I think you're vastly OVERestimating the integrity of the community.

And just because a video game doesn't have to create a safezone for racial tolerance, doesn't mean we should allow it to happen. Any steps taken to prevent it are better than none.
For as terrible as League players' behaviors are getting, don't let the CoD mentality make its way into League.

From your general arguments, I think I can distill the debate down to this:

Do the benefits of improved communication out weigh the potential for abuse?

In my experience, the benefits are common and the abuse is rare. The abuse is probably more impactful, but this is mitigated by infrequency and of course the optionality of the whole system.
I think it's worth it.

My main issue with this is:

Most of the times people won't even use either

If people don't even have an intention of using it, what's the point of it? How much benefit could it actually provide if no one's going to use it anyway? It gives some people an unfair advantage over the others, much moreso than duo queueing does, and it gives people another reason to be toxic to others just as much as lolking/lolnexus does, if not more. Whether or not the features could improve LoL if implemented into the game, 3rd party programs should not be tolerated.