I think to some it up, there's been massive emphasis on Building, which has kept the building factions in the game while isolated everything else. Lots of RP factions crumbled and since Odium's just about gone there is less forum-side faction warfare to make people laugh/cry/scream/shout etc. Moreover, since the time when EE closed, publicised faction warfare (i.e. faction warfare on servers and off, across servers and on forums) more or less died down and is now much less than it was.
Another reason for the 'abandonment' of Starmade by made people was the steam advertisement. When steam first started working with Starmade it brought tons of steam players onto Starmade. Now steam doesn't really showcase Starmade so there is 99% less people who accidently see Starmade adverts. Moreover, players who played Starmade as a secondary or tertiary game find new games and Starmade just can't compete with EVERYONE's interests so it can't hold all the players in.
I think there would have to be a few things to reverse this:
A) publish Starmade somewhere else or begin an advertisement campaign e.g. by getting someone like pc games or IGN to right reviews of Starmade, drawing their followers to Starmade.
B) get EE back up and draw all faction warfare and politics into it as it used to be during 'the golden age' of ElwynEternity.
C) Get a major update and make it very public which will appeal not only to building factions, but to all factions (RP factions, offensive factions, mercenaries, pirates, spies...EVERYONE)