Agreed. I still think DJ Sona should've had a voice since, mute or music aside, she's still a telepath. The retcon of the IoW didn't change that about her and for her "ultimate" skin to be incomprehensible is a damn shame. I think PF Ezreal and SG Udyr have done more for their respective characters than DJ Sona ever will.
But more on point, what with the way the lore has been wibbly wobbly lately, a champion's voice and interactions are the closest thing we've got to understanding who the character is. If you don't give a crap about character development or lore, then this probably doesn't affect you nearly as much as it does me or any of the other countless people that regularly make threads about lore. Riot has been doing some things to push lore along such as Kalista's promo video or that little bit about Bilgewater and the Shadow Isles. That's all neat and great, but it's not enough to satisfy.
For example, there are people that play Jinx because they like her kit. Rockets and bullets with lasers are always neat. Then there are people that play Jinx because they like who Jinx is. Without a voice, you lose so much of what makes Jinx "Jinx." I said in a complaint a few weeks back that a character's voice is their window we use to see who they are and what they know. We learned more about who the Ruined King was than we ever had in all of League's lifetime the moment we bought that sword as Kalista. Without her voice and her insight, we wouldn't have known and we would still be speculating on random what-ifs with no sense of direction. Now at least we can focus our thoughts somewhere if we wanted to.
Gnar's voice is fine with me. He speaks in baby talk because that's what he is essentially, but through his taunts with various champions, you can get this sense that he's trying to learn and fit in with everyone else. Lines such as "sharg" and "demaglio" come to mind. Rek'Sai's cracks and growls are fine for her character as well. In her promo, she's this menacing beast that terrorizes Shurima and with her alien voice over, it helps to really drive that point home. If you heard that clicking noise she makes in real life, you'd naturally freeze up and start praying to whatever god you believed in. Regardless, you still get a feel for who the character is through the interactions they do have.
I think these are all neat ideas but there comes a point though when you have to step back, from a narrative point of view, and ask whether or not you're milking a neat idea dry. Bard speaking in brass is probably a neat idea but he comes off the back of DJ Sona and her inaudibleness, Rek'Sai and her clicks, and Gnar with his gibberish. To note, I am aware Kalista and Azir came out between Gnar and Rek'Sai's release but is that enough of a window? Our most recent meaningful lore dumps happened during major events that are relatively few and far between. One of which happens yearly with only two, if I recall correctly, lore dumps centered around it and the Shurima event. I feel like there is a plethora of missed opportunities to meaningfully advance some kind of lore with this recent collection of champions.
tl:dr Agree with the OP. I'm fine with champions not having much to say sometimes, but lately it's too quiet on the Rift. I'd prefer them to speak more often, telepathically or vocally.
Edit: Point made. Bard's lore just hit the pbe and I can summarize it in one line. "Bard does stuff and keeps the universe from destroying itself." I wish I was being snarky or an ass about it, but his lore honestly doesn't tell you much of anything. He just...does stuff. How? Why? If he talked or if someone talked to him, then maybe. Right now though? There's so little here to focus on that you have to start asking "Was this honestly worth writing?"