I understand what the goal of Dynamic Queue was. I understand how it works, and that there are several advantages to having it the way it is. I do not, however, think it justifies the removal of Team Builder.
The main issue with the removal of Team Builder is the removal of the ability to play what you want, with who you want, who is also playing what they want. As an example, a friend of mine and I like to duo in the bot lane together because we've spent a lot of time learning each other's playstyles, working with what champions the other likes to play, etc. In Team Builder, we could walk in, party up, choose Marksman Bot and Support Bot with whatever champions we wanted to play and learn, and then play with those champions in those positions. When we tried to do so in the dynamic queue, out of the first 5 games we played, we managed to grab the bot lane once, and even then, we didn't get to play what we wanted due to the bans.
In Draft or Blind Pick, you don't/didn't always get the position you wanted, or champion for that matter, but people were generally willing, from what I saw, to allow a duo to lane together because players who know each other well enough to feel good duo queuing together will typically do better than a pair of guys who've never played a match together in their life.
Dynamic Queue is supposed to emphasize team play, and it's a great way for random solos to communicate with each other, but when I play with friends or want to practice my Bard play against actual players without going into ranked or potentially not getting support, it doesn't fill my needs as a player. That's why I want Team Builder (and for the same reasons, Duo Queue) back.
As a side note that I also feel is worth mentioning, Team Builder was also the best place to go when you wanted to try something off-meta, like Vi Support or Jungle Ahri. Between the longer queue times and Pick Intent being a double-edged sword in that people can choose to dodge and cause you to wait because they didn't like your off-meta pick, meaning if you want to play something unusual, you essentially have to lie about your pick, which isn't promoting good team play either.