I'd say there are more on the team who could communicate better (CertainlyT, for example, I don't think communicates at all, and Cactopus I think has had times where he's flat-out done more harm than good), but I fully agree that there are also several Rioters who are doing a great job already, including many more than the ones cited above, and who deserve to be commended.
Personally, my problem with Riot's communications in recent times is that, oftentimes, Riot's idea of communication has come down to talking at the players, rather than with them. We get neatly wrapped dev blogs and occasional video clips where a Rioter basically monologues the whole time, or talks only with other Rioters, and once those things are posted, no comment given on those spaces really generates further official discussion. Even on Meddler's Quick Gameplay Thoughts, where he engages in the comments, player concerns may get a response, but practically never influence the actual development process. In general, the whole procedure feels set in stone, so we're only learning about what will happen, instead of being able to impact on that.
This is where RiotRepertoir's recent posts come in, because even though the broad lines of certain projects are fixed, players on the Boards are being proactively asked by the developers for feedback and suggestions, which have a genuine chance of affecting the final product. Jinxylord did this with the Rengar revert, which is why it turned out so successful. Because we are being invited to participate in the development process, rather than just told of a feature after all of the decisions have been made, we as a community feel empowered, and are therefore much more disposed to give constructive feedback. Because we are also being placed on an equal, mutually beneficial relationship with the development team, that relationship also translates to mutual respect for most players who participate, which in turns generates much better appreciation for Riot. Because we also have to grapple with the inherent difficulty in coming up with a workable solution to a problem, and even identifying and defining problems in the first place, we also get to appreciate the work Riot does much more, and are therefore less likely to dismiss Rioters and their work.
If there is one criticism I have of this, it's that so far this kind of enriching, two-way discussion has only been sporadic, when in practice it should be happening all the time. So far, we only get this kind of communication from some Rioters, who only get to do so when they're not knee-deep in other work. As such, while things are going really well now, they may be much less likely to do the same once Repertoir or Jinxylord have to pull back due to other commitments. In this respect, Riot really needs to work on making this kind of communications a proper, fully-fledged system, one where Rioters are scheduled to communicate with players and invite them on design work on a regular basis, rotating as some members of the team enter or leave other important projects in order to render these communications consistent. I feel we're already experiencing significantly positive returns from this current bout of good communications, and continuing on this good trend could permanently change League, the Boards and the entire player community for the better.