As Earth was the game I grew up with, it is saddening to see FFA dwindled so far from its heyday. The following are reasons for the decline

Divide between the haves and have-nots
Sounds familiar in certain real societies, doesn't it? Big clans hold all the power in FFA. Newcomers are treated badly and suffer serious reprisals for minor offenses. Unspoken rules and game etiquette are hard to learn. It is almost impossible to net even to the top 10 as 16 member tags.

Concentration of techers
Once upon a time, it was possible to get enough of a head start as a industrialist so that the techers wouldn't ever be able to catch up. A lot of people will remember the fat 60k land indies 10 years ago that the 20k land techers couldn't outgrow. In all the time I've played earth, techer vs indy was probably the most exciting race to watch or participate in. It was the proverbial turtle vs hare. But now, the turtle runs as fast as the hare.

The reason is simple. With record low military costs for techers due to landfarming, it is possible to have 0 military across the board. The land advantage that commies used to be able to achieve just isn't there anymore.

Landfarming
No matter what is said about how people should be able to use their own countries in whatever way they desire, this is one of the most serious problems of the game. Attacking other people is just not even close to as effective as landfarming. The major element of aggression is now solely directed to newcomers and 16 member tags who are helpless.

And unlike in real societies, the helpless can simply leave and never come back.