The alliance system introduced created 2 huge blocks because the maximum number of possible allies were up to 3 nations.
The total number of nations then were 8 (including pirates, not allowed to ally), so the creation of the 2 blocks was something to be expected.
The biggest rvr clans have lost a considerable amount of players since the end of the last big war. For example, BF had over 40 players connected at the same time while in recent streams those numbers have gone down to ~10. Seems that quantity of pvp-rvr targets are not enough to keep them interested.