I think a lot of the issue stems from the the friendly Rioters, like you, taking the time to talk to us on stuff that you're able to talk about, but the issues those people are able to talk about haven't been the issues players need Riot to talk about.
Someone already brought up the whole "People start shouting 'Nerf Lee Sin! Fix the Servers!'" at you, and it's not your area of expertise. But the people whose area of expertise it does belong to do not engage in legitimate discussion with the players these days.
Phreak is the closest thing we've gotten to balance discussion in ages, and he's not on the balance team any more, he's a shout-caster instead, and even he left the last thread once the discussion went into more depth than his "Win rate = balance" defense (shortened version, no disrespect meant).
We finally after ages got some insight into the server roadmap, and that was great! I'm sure a lot of people were glad to see the discussion come up.
The point is that the Rioters who will talk don't work on the issues that are infuriating the playerbase and need talked about and fixed. The ones who do work on the issues, however, insist on either completely ignoring the community, or writing off anything they say as "nah, I work at Riot so my opinion > your logic" and hop out of threads after a few short posts.
I'm well aware the community is full of anger sometimes, and much of it is unfair anger, but the frustration is certainly reasonable. I think many of us are just tired of the same balance issues, and the people responsible plugging their ears and shouting "LALALALA" and running out of a thread the second they see an argument that more strongly supports a claim against what the people responsible say is the case.
If you don't work work in Balance, Design, or Systems, I can (almost) promise you that you have nothing to fear because the issues that NEED talked about are all in Balance, Design, and Systems. But those people don't come talk about them. As long as you're working on skins, chances are nobody (at least nobody who knows you work in skins, anyway) is going to rage at you, because everyone is happy with the skins (I think? I know I am, though I'm still waiting for my Dragonmaster Swain and Jurassic Kha'zix -sad face-). The topics people aren't happy with are the ones that are vital to a healthy game state and balanced upcoming ranked season, yet the Rioters who could speak with us about them won't do it either out of fear or spite or just plain apathy.
You know we went through almost an entire preseason (y'know, the thing where sweeping balance changes can be made to adjust for the upcoming ranked season?) without Rioters coming to discuss major balance/design issues? Like, at least Warwick got noticed, thank god, but I think a blind person who doesn't even play League would've noticed Warwick was broken. Anything less obvious than that got no discussion, and that's why people are mad. Sure, we may get a post here or there, but I'm talking about real discussion and debate over balance and design issues, that extends beyond reds coming in and saying "Nah, what I say is fact, your information is irrelevant, peace I'm out betches".
We usually hear the "sorry, those guys are just working too hard to post" (which, and I'm well aware I don't work there, but I think is a super lame excuse and probably an unfair one after a whole preseason), or the "we read your threads! We value your input!... as long as it's in line with what we believe" responses. Suffice to say, that's not.. uh.. ideal... And I think the community just sort of gets forced to bottle up a bunch of rage because we know these things are important, because we're playing the game and are affected by them regularly.