I still play BF4 and think its the best of the franchise. It's definitely not perfect (I'm talking to you TV missile bug), but the minor issues could be fixed. The foundation of the game is great. I do miss some of the BF2 maps thought.
I was really hoping this was going to be an evolution of BF4 and in some ways it is and in many ways it is not and can never be.
Vehicle game-play is just really bad in BF6 and I don't think anything aside from a ground up overhaul could fix it.
Trying to make this a big tent game for everyone was a mistake outside of what they thought would be a profit landfall.
They could have possibly made more people happy by making portal good but its not even an afterthought.
I also think the idea of giving everyone the ability to run their own server just dilutes the player base and makes it feel cheap.
If you wanted to run a server for BF4 it would cost you money above what you paid for the game. This limited the amount of servers and that was good. It created a real community that had to put work in to make the server survive. Now, lets say I go out of my way to do a recreation of a may I enjoyed in the past, that experience code goes out to everyone and the work I put in is automatically diluted by everyone piggybacking on that creation.
At an immediate they need to bring back clans and a way for more than 4 friends to join a match at a time if they want to run matchmaking.
And in total seriousness, there were maybe 3 times where I randomly had a good squad of unknowns and we all chose to stay together. Two of of the three didn't even put us together in another match and I was booted back to the main screen.
Private servers are great in that you know the rotation and you stay with the player base. You develop friendships because you see the same names over and over. The current system prevents that. Its like they are purposely keeping players at an arms length from each other.
I made a lot of friends in BF4 and a small amount in BF1. I still play with them to this day. I cannot say I friended a single person after BF1 because of matchmaking.