Just because a map was shared between them, doesn't mean BM and War Islands have much in common gameplay-wise.
I know; I've played on both. But since the War Island mini-game isn't popular, I'm not sure that the original SEI/SWI will be the boon that people are making it out to be.
I think that the problem with the game is the players, myself included. When I started playing, I was 23 and had no kids. Now, I'm 29 and have 2 kids. I simply don't have the time to write big roleplays or scheme or politic or whatever; I even have an empty character slot because I'm barely able to play 3 characters, let alone 4. The character base has aged, and has more things to do.