I am not a fan of having premades on my team, or equally, on the enemy team.
It is not a balanced match when you are put against Premades of 3 or 4 players, when your team consists of all solo players. They have a far greater ability to coordinate and work together versus people playing alone. "Teamwork makes the dream work."
You can ping and type all you want with your other solo teammates, doesn't mean they are going to listen. Meanwhile the premade you're up against is setting up plays and grouping and splitting with much greater precision and effectiveness, because obviously they are much more likely to work together as a group.
For example, they can plan that the Yi is going to dive the back line, and the Zilean is going to ult Yi, and then when everyone collapses on the Yi and kills him (temporarily), the Amumu is going to Ult the whole team followed by a Malphite ult, followed by a Zilean stun, then Yi revives and kills everyone. That's easy to coordinate when you're a premade. Try doing that play with a Solo team: instead, Yi will just die immediately with no Zilean ult, Zilean will spazz out and go farm krugs, meanwhile Malphite will ult all the way to Beijing and buy himself some chow mein.
Also: Premades are **almost always** toxic, especially to their own teammates who aren't part of their little friendship circle. Countless times I've been flamed by the whole team, when I haven't really done anything particularly wrong (missed a skillshot, or made some other minor error), then the whole team starts raging at me for the rest of the game and I wonder to myself 'Wow, what is this world coming to?' Then I check op.gg after the game and see that it's the same few people queuing game after game. Surprise, surprise.
So really, as a solo player, I don't really want Premades on my team, nor on the opposing team, and would be overjoyed if premades were matchmade with other premades. I am sure there are more than enough players to make this work, when queue time is around 15-30 secs for me... except maybe at 3AM server time if there is a shortage of players, you might end up with premades, but that'd be understandable.
I know Riot probably won't implement such a change, but it's worth voicing this point anyway...