The match list was, according to Muse, a "performance bottleneck" or something.
I can't really blame them, because the match list refreshed itself every few seconds with all the matches that matched your filter, so I guess that at least does some performance issues for Muse servers. You can see in the custom matches that they tried to solve the issue by limiting it only to friends in matches and actually having a "refresh" button instead of refreshing automatically.
Another major argument of Muse was that "a lot of empty lobbies are created and instead of joining those, people create more lobbies". It is kinda true, I have seen a lot of half empty lobbies or lobbies with even less people in them and it would just take forever to fill them. One time we had a lobby with two full ships on our side and on the enemy team was not a single person, so I went afk for 15 minutes. Only when I came back were people ready to start. These things wouldn't happen with matchmaking.
The lobby timer was defended by Muse by saying things like "but the old lobbies never started in a reasonable amount of time or people would draw them out forever by switching to spectater slot!". They basically wanted to get rid of "Lobbies of Icarus" and promote the air-ship mini-game, which ended being a game changer to how the lobby meta worked. What I was always wondering about was why would you need the lobby timer if matchmaking is supposed to fill the lobbies as quickly as possible, which results in lobbies starting sooner? But I guess it gets the job done and if you don't like it, make a custom lobby and invite people that actually do fit your matchmaking ranking.
Recommended loadouts defintely helped start the matches quicker and if people refused them I tried to talk them into taking at the very least the correct ammo type or a combination of engineering equipment that actually works. People outside yourself cannot see what loadouts you recommend, as far as I am aware, so people that join mid-game still have to guess on what to take, but matchmaking doesn't like running matches anyway. Custom lobbies at least still shows you games that are running when your friends are in them.