So after reading almost every post in this thread (i believe, i may have skipped a QQ or Troll post here or there, 14 pages, i was bound to miss a small handfull), I did not see any reasoning behind "no pre-made teams" other than stacking.
Well, here's another to consider, as the previously mentioned reason has been beaten into the ground and repeated over and over again:
You get 3 eden stars for every win and 1 for every loss, those stars are used to buy warrior chests and clas medals. If you allow pre-made teams, you run the risk of players timing it to attempt to get their teams to fight each other which can be used to abuse receiving medals and eden stars to buy more medals or warrior boxes.
in random, there's a far less chance of this type of match swapping, which keeps the items received to be less exploitable.
Also, argument as to why randomized teams are good. If players use the same team over and over in every match, they lose the possibility to meet other players and learn how to use teamwork with players they would either not know or only try to kill otherwise. It's better for strengthening the community.
The only suggestions I have currently are:
-As previously mentioned, keep PVP as 24/7. With different time zones, jobs, school, and combinations of these. Three 2-hour slots will be a problem for many.
-Partying: I think all members of a team should be automatically added into a party with each other. It's a pain to have to start a party for every match you start.